Quizlet-inborn errors

A 21 year old woman with phenylketonuria discontinued the PKU diet in early adolescence. She presents to her

OBGYN for her first prenatal visit. Her husband does not have the disease.

Which of the following is the best course of action?

A. Since the child is heterozygous for PKU, no special action needs to be taken.

B. The patient blood phenylalanine levels should be monitored and appropriate action taken if they become too high.

C. The patient should try to avoid excess phenylalanine in her diet by restricting protein intake

D. The patient should immediately resume the PKU diet and have her blood phenylalanine levels monitored on a

regular basis.

D

36 hours after birth, a term male infant presents post seizure. The infant appeared well at birth but on the second day

of life developed irritability, vomiting, feed refusal, and becomes increasingly lethargic. Blood gas analysis shows a

respiratory alkalosis and plasma ammonia concentrations are found to be 360 micro-m/l (normal for a full term infant

is <50 micro-m/l).

Which of the following is most consistent with these symptoms?

A. Branched-chain alpha-ketoacid dehydrogenase complex deficiency

B. Glucose 6-phosphatase deficiency

C. Lipoprotein lipase deficiency

D. Ornithine transcarbamoylase deficiency

E. Phenylalanine hydroxylase deficiency

D

Which statement regarding phenyketonuria (PKU) is FALSE?

A. PKU is the most common disorder of amino acid metabolism in the United States.

B. PKU symptoms result from an excess of the essential amino acid, phenylalanine.

C. PKU is only caused by a mutation in the gene for phenylalanine hydroxylase.

D. A phenylalanine restricted diet must be implemented soon after birth for classic PKU

E. Untreated patients with classic PKU will be mentally retarded.

C*

Which of the following statements regarding inborn errors of metabolism is FALSE?

A. Often autosomal recessive in inheritance.

B. Can involve synthesis or breakdown of biological compounds.

C. Often result in non-specific symptoms.

D. Accumulation of toxic compounds often contributes to the pathogenesis.

E. Treatment strategy often includes providing patients with the substrate of the deficient enzyme.

E*

A two-week-old infant, who appeared completely normal from birth until that morning, was brought to the

emergency room because of he was unresponsive when his mother tried to feed him. Patient was afebrile. The

patient exhibited metabolic acidosis and urine showed no ketones. Which of the following is the most likely

diagnosis?

A. Biotinidase deficiency

B. Medium chain acyl-CoA dehydrogenase (MCAD) deficiency

C. Maple syrup urine disease

D. Galactosemia

E. Phenylketonuria

B

On her first visit to the pediatrician, an infant is found to have bilateral cataracts. Total galactose level in red blood

cells was elevated. Galactose-1-phosphate level was normal. Which of the following tests will be indicated to assist in

making a diagnosis?

A. Galactose kinase enzyme activity in red blood cells

B. Galactose-1-phosphate uridyl transferase activity in red cells

C. Mutation analysis of the galactose-1-phosphate uridyl transferase gene

D. Tandem mass spectrometry to look for elevated levels of glucose

A

A couple has recently migrated from a rural village in Poland. They have a six- year-old child with mental retardation,

microcephaly, decreased skin and hair pigmentation and a musty odor to the urine. The family history is otherwise

negative. Which of the following is most likely diagnosis for the child?

A. Alkaptonuria

B. Galactosemia

C. Oculocutaneous albinism

D. Phenylketonuria

E. Tyrosinemia

D

Which of the following is not restricted while prescribing dietary therapy for a young infant with phenylketonuria?

A. Breast milk intake

B. Tyrosine intake

C. Phenylalanine intake

D. Protein intake

B

Your patient with phenylketonuria has just announced that she is 18 weeks pregnant. She has been off her

phenylalanine-restricted diet for several years. If she does not make changes to her diet, what is her child most likely

to have?

A. increased tetrahydrobiopterin level

B. low phenylalanine levels due to placental barrier

C. low tyrosine levels due phenylalanine hydroxylase deficiency

D. Microcephaly and probable future cognitive defects

D

A child is referred to you following an abnormal newborn screen that showed elevated medium chain fatty acids.

What should be your recommendation for the care of this infant?

A. avoid carbohydrates

B. feed the child every 3-4 hours

C. prevent intake of carnitine

D. switch to a diet rich in fish oils

E. supplement the diet with tyrosine

B

A 7-day old baby who has been lethargic with poor feeding, poor activity and a weak cry presents to the local

emergency department (ED) where the patient was found to be hypotensive, tachycardic, with poor capillary refill.

Electrolyte panel showed hyponatremia, hypoglycemia, and hyperkalemia. You had the ED nurse call the State

Department of Health for newborn screen results which came back positive for congenital adrenal hyperplasia (CAH).

What is the most likely cause of the CAH?

A. 5 alpha reductase deficiency

B. 11 hydroxylase deficiency

C. 21-hydroxylase deficiency

D. 17,20 lyase deficiency

C

You confirm the diagnosis of CAH and note that the patient has apparent male external genitalia, empty scrotum,

microphallus, and hypospadias on physical exam. Pelvic ultrasound showed normal uterus and ovaries. What would

the chromosome analysis most likely show?

a. 46,XY

b. 46,XX

c. 46,XX/46,XY

d. 45,X/46,XX

B

Which of the following pregnancies is at highest risk to result in a baby with birth defects if no dietary treatment is

implemented during pregnancy?

A. The mother is a dihydrobiopterin deficiency carrier and the father is a PKU carrier.

B. The mother is a PKU carrier and the father is a dihydrobiopterin deficiency carrier.

C. The mother is a PKU carrier and the father is a PKU carrier.

D. The mother is a PKU carrier and the father has PKU.

E. The mother has PKU and the father is a PKU carrier.

E

Defects in which of the following enzyme results in oculocutaneous albinism?

A. Fumaroacetoacetate hydrolase

B. Homogentisic acid oxidase

C. Phenylalanine hydroxylase

D. Tyrosinase

E. Tyrosine hydroxylase

D

Which one of the following is part of the optimal management of a patient with phenylketonuria?

A. A phenylalanine-free diet

B. Diet drinks containing aspartame

C. Medium-chain triglycerides supplementation

D. Overnight nasogastric formula feeding

E. Tyrosine supplementation

A

Which one of the following disorders is a defect in tyrosine metabolism?

A. Albinism

B. Carbamoyl phosphate synthetase deficiency

C. Gout

D. Homocystinuria

E. Methylmalonic acidemia

A

Which one of the following inborn errors of metabolism is not characterized by a typical odor?

A. Alkaptonuria

B. Branched-chain acyl CoA dehydrogenase deficiency

C. Glutaric aciduria type 2

D. Isovaleric acidemia

E. Phenylketonuria

A

A number of genetic diseases can be strongly suspected (no pun intended!) based on the unusual body odor

emanating from the patient when untreated or poorly treated. Which one of the following diseases does not belong

to this group?

A. Cystic fibrosis

B. Diabetic ketoacidosis

C. Isovaleric academia

D. Maple syrup urine disease

E. Phenylketonuria

A

Which one of the following plays a major role in the degradation of long chain fatty acids?

A. The Alanine-Glucose Cycle

B. The Carnitine - Acylcarnitine Cycle

C. The Cori Cycle

D. The Krebs Cycle

E. The Urea Cycle

B

A 9 day old infant presented to the emergency room with recurrent vomiting, hypotonia, respiratory distress and was

found to have profoundly positive anion gap metabolic acidosis and hyperammonemia. Moreover, he emits a strong

sweaty feet odor. Of the following inborn errors of metabolism, which one is the most likely?

A. Diabetic ketoacidosis

B. Isovaleric acidemia


D. Methylmalonic acidemia

E. Ornithine transcarbamoylase deficiency

B

A poorly-grown 2 month old infant has jaundice, easy bruising, lethargy and decreased consciousness. His laboratory

studies showed hyperchloremic metabolic acidosis, markedly elevated liver enzymes, hyperammonemia, and

hypoalbuminemia. His urine showed increased protein, glucose, sodium, calcium and phosphate excretion. Of the

following conditions, which one is the least likely?

A. Galactosemia (galactose-1-phosphate uridyl transferase deficiency)

B. Hereditary fructose intolerance (aldolase B deficiency)

C. Kwashiokor

D. Oculocutaneous albinism (tyrosinase deficiency)

E. Tyrosinemia (fumarylacetoacetate hydroxylase deficiency)

D

Other than being a substrate for cholesterol synthesis, 3-hydroxy-2-methylglutaryl CoA (HMG CoA) is also a substrate

for

A. fatty acid synthesis

B. glutamine synthesis

C. ketone synthesis

D. purine synthesis

E. sphingomyelin synthesis

C

One week after taking a dose of chloroquine for malaria prophylaxis, a man of Sicilian descent was found to have

pallor, jaundice and weakness. His hematocrit was 20%. The most likely diagnosis among the following is

A. acute intermittent porphyria.

B. butyrylcholinesterase deficiency.

C. glucose-6-phosphate dehydrogenase deficiency.

D. malignant hyperthermia.

E. methemoglobinemi

C

Which one of the following interventions is the most effective in curbing catabolism in a patient with an inborn error

of metabolism who is in acute metabolic decompensation?

A. Carnitine supplementation

B. High dose intravenous glucose infusion

C. Intravenous bicarbonate infusion

D. Mechanical ventilation

E. Oral administration of cornstarch

B

Which one of the following compounds cannot give rise to the net synthesis of glucose?

A. a-ketoglutarate

B. glycerol

C. lactate

D. leucine

E. oxaloacetate

D

Which one of the following groups of amino acids is the most important in the synthesis of neurotransmitters?

A. Aromatic amino acids: phenyalanine, tyrosine, tryptophan

B. Branched-chain amino acids: valine, leucine, isoleucine

C. Non-polar aliphatic amino acids: alanine, glycine, methione

D. Positively charged amino acids: arginine, lysine, histidine

E. Uncharged polar amino acids: serine, threonine, cysteine

A

Which non-essential amino acid is synthesized from an essential amino acid?

A. Alanine

B. Aspartate

C. Glutamate

D. Proline

E. Tyrosine

E

Which one of the following amino acids is purely ketogenic?

A. Alanine

B. Isoleucine

C. Leucine

D. Tyrosine

E. Threonine

C

Patients with Marfan syndrome and homocystinuria can both have lenticular dislocation. To distinguish between

these two diagnoses, which one of the following diagnostic tests would be most specific?

A. Body height

B. Ophthalmologic examination

C. Platelet count

D. Plasma ammonia concentration

E. Quantitative urine amino acid

E

The degradation of which one of the following amino acids will not contribute any substrates for gluconeogenesis?

A. Leucine

B. Methionine

C. Proline

D. Threonine

E. Tyrosine

A

Which one of the following signs or symptoms is not a common feature of homocystinuria?

A. Developmental disability

B. Lenticular dislocation

C. Marfanoid habitus

D. Renal stones

E. Venous thromoboembolic events

D

Elevation of which one of the following has been shown to increase the risk of deep-vein thrombosis?

A. Cystathionine

B. Homocitrulline

C. Homocysteine

D. Methylene tetrahydrofolate

E. Methyl cobalamin

C

Deficiency of which one of the following causes significant elevation in plasma homocysteine?

A. Aspartate aminotransferase

B. Cystathionine synthetase

C. Dihydrofolate reductase

D. Glutaminase

E. L-glutamate dehydrogenase

B

Which one of these molecules would not be part of treatment for an inborn defect in the urea cycle?

A. arginine

B. glucose

C. glutamine

D. phenylbutyrate

E. sodium benzoate

C

Urea synthesis in mammals takes place primarily in the:

A. brain

B. intestine

C. kidney

D. liver

E. muscle

D

In the bloodstream, two major amino acid carriers of ammonia from the tissues to the liver are:

A. Alanine and citrulline

B. Alanine and glutamine

C. Arginine and asparagine

D. Asparagine and glutamine

E. Glycine and lysine

B

A 44 year old man comes to your office complaining of headaches, vomiting and episodes of confusion. On your

careful history, you learn that he has a lifelong history of "atypical" migraines with vomiting and incoordination,

especially when he consumes meat, and therefore he follows a vegetarian diet. You learn that his sister's son

developed hyperammonemic coma at 5 days of age and was recently diagnosed with ornithine transcarbamoylase

(OTC) deficiency.

Which one of the following laboratory findings is least compatible with the diagnosis of OTC deficiency in this man?

A. High blood urea nitrogen

B. High plasma glutamine

C. Hyperammonemia

D. Low plasma arginine

E. Low plasma citrulline

A

Watermelon is very rich in citrulline (the Latin word for watermelon is citrullus). Thus, watermelon should be avoided

in patients with

A. Argininosuccinate synthetase deficiency

B. Carbamoyl phosphate synthetase I deficiency

C. Cystathionine synthase deficiency

D. Ornithine transcarbamoylase deficiency

E. Pyruvate carboxylase deficiency

A

A newborn is found to have classic phenylketonuria. The most appropriate treatment is

A. Administer a drug to chemically conjugate phenylalanine for renal excretion

B. Total protein restriction

C. Total phenylalanine restriction

D. Total tyrosine restriction

E Restrict phenylalanine intake but provide enough for growth needs

E

In patients with untreated classical phenylketonuria, which one of the following becomes an essential amino acid?

A. Arginine

B. Asparagine

C. Serine

D. Tetrahydrobiopterin

E. Tyrosine

E

New parents bring their 1-week-old baby boy to the pediatrician's office and report that he is not feeding as well over

the last 24 hours and that his diapers have an odor like sweaty feet. Which of the following disorders is the most

likely cause of this child's problems?

A. Isovaleric acidemia

B. Maple syrup urine disease.

C. Methylmalonic acidemia.

D. Phenylketonuria

E. Propionic acidemia

The odor of sweaty feet is classically associated with isovaleric acidemia. The odor of untreated PKU is sometimes described

as having a mousy odor. The odor of untreated maple syrup urine

disease is as suggested by the name of the disease. Odor is not a prominent feature for propionic or methymalonic.

The correct answer is A.

New parents bring their 1-week-old baby boy to the pediatrician's office and report that he is not feeding as well over

the last 24 hours and that his diapers have an odor like sweaty feet. Which of the following laboratory tests is most

likely to provide a definitive diagnosis?

A. Comprehensive Metabolic Panel

B. Plasma amino acids

C. Plasma ammonium level

D. Urine amino acids

E. Urine organic acids

Urine organic acids will provide a characteric profile that allows for clinical diagnosis.

The correct answer is E

A four-day-old infant boy is brought to the emergency room lethargic and no longer taking his formula. A metabolic

profile reveals metabolic acidosis and his ammonium level is normal. Which of the following diagnoses is most likely

to be found with subsequent metabolic screening studies?

A. Citrullinemia

B. Maple syrup urine disease

C. Methylmalonic acidemia

D. Ornithine transcarbamylase deficiency

E. Proprionic acidemi

High ammonia would be a feature of all of these disorders except maple syrup urine disease.

The correct answer is B.

You are seeing a couple whose first child is a Duarte/classical Galactosemia genetic compound heterozygote. His

parents (who have not been tested) ask about the risk for their next child to have classical galactosemia (Gal/Gal).

Knowing that the frequencies of the Duarte (1/27) and Gal (1/278) alleles, which of the following do you think is their

risk to have a Gal/Gal child?

A. 1/278

B. 1/278 x 2/3

C. 1/278 x ½

D. 1/278 x 2/3 x ½

E. 1/278 x ½ x ½

One parent must be a Gal carrier and the other a Duarte carrier. There is a possibility that the parent who is a Duarte carrier is

also a Gal carrier. Such individuals have about 25% of normal gal activity, which would not produce clinical signs of

galactosemia. The risk that the other allele in this parent is Gal is 1/278. In this case the risk to a child would be ¼. Therefore

the overall risk is 1/278 x ¼.

The correct answer is E.

You are notified by the state newborn screening laboratory that a seven-day-old neonate, born at 33-weeks gestation

and is receiving antibiotics for possible sepsis and total parenteral nutrition (TPN). He was found to have a

phenylalanine level (Phe) of 4.8 mg/dL (291 (M). Which of the following interventions is the most appropriate next

step in evaluating or managing this child's care?

A. Stop (TPN) briefly and remeasure Phe on glucose and IV fluids.

B. Modify antibiotic coverage patient is probably receiving

C. Monitor the phenylalanine level weekly over next month.

D. Restrict the infant's phenylalanine intake

E. Obtain urine for assessment of biopterin metabolite levels.

There are two reasons why this infant may have an elevated phe on newborn screening - immaturity of the HPPD enzyme and

TPN. The best way to exclude an inherited disorder in phe metabolism would be to stop the TPN briefly (~4-6 hr) and provide

calories with glucose and

recheck the phe off the TPN.

The correct answer is A

A nine- month-old infant contracts a viral illness and is unable to take her usual amount of formula over the previous

24 hours. She is found dead in her bed the following morning. Which of the following disorders accounts for

approximately 5% of cases of sudden infant death syndrome (SIDS) and is the most likely cause of this unfortunate

infant's death?

A. Glutaric aciduria Type I

B. Glycogen storage disease Type III

C. MCAD deficiency

D. OTC deficiency

E. Propionic academia

MCAD presents with hypoketotic hypoglycemia and can resemble Reye syndrome or SIDs. Although initially it was thought

that a higher percentage of cases of SIDS were likely due to defects in fatty acid oxidation, prospective and retrospective

studies now demonstrate that this accounts for ~5% of SIDs. While OTC and propionic acidemia patients can occasionally die

unexpectedly, there are usually some warning signs - vomiting, lethargy, irritability. GA I presents with MR, a movement

disorder, and macrocephaly. GA II could be a rare cause of

sudden death.

The correct answer is C.

You are asked to evaluate a one month old asymptomatic girl who had an elevated tyrosine on newborn screening.

Succinylacetone testing was subsequently positive. Which of the following interventions is the best initial course of

action for this infant?

A. Place the infant on a low phenyalanine diet

B. Place the infant on NTBC and a low tyrosine diet

C. Reassure the family that the infant had transient tyrosinemia of the newborn

D. Refer the infant for evaluation for a liver transplant

E. Repeat tyrosine levels at monthly intervals

The elevated tyr + succinylacetone is diagnostic for Type I tyrosinemia. Current standard treatment is NTBC + low tyr diet

(tyrex formula). The advent of newborn screening and NTBC has resulted in a markedly reduced need for liver

transplantation.

The correct answer is B

Malignancy is a major risk in which of the following metabolic disorders?

A. Cystinosis

B. Hurler syndrome


D. Propionic acidemia

E. Tyrosinemia

Some autosomal recessive disorders with substantial risk of malignancy are glycogen storage disease type I, tyrosinemia,

hemochromatosis, and others less prominently. Immunodeficiency disorders and DNA repair disorders also relevant.


Which of the following abnormalities is the most likely diagnosis in a 3-day-old infant who develops lethargy,

vomiting, respiratory alkalosis and hyperammonemia with undetectable plasma citrulline and massive orotic

aciduria?

A. argininosuccinate synthetase deficiency

B. carbamylphosphate synthase I deficiency

C. nonketotic hyperglycinemia

D. ornithine transcarbamylase deficiency

E. propionic acidemia

The clinical features are classic for a urea cycle disorder. Levels of citrulline on amino acids are key to deciding which disorder

is present. Undetectable citrulline is found in males with OTC and CPS deficiencies. In OTC, carbamyl phosphate is shunted to

pyrimidine synthesis resulting in high orotic acid. In CPS deficiency, no carbamyl phosphate is made and so there is no

elevation in orotic acid.

The correct answer is D.

An asymptomatic infant who is found to have hyperphenylalaninemia on newborn screening should

be tested for which of the following associated problems?

A. biopterin synthetic defects

B. catechol-o-methyltransferase

C. liver disease

D. microdeletion deficiency of chromosome 12

E. porphyria cutanea tarda

Tetrahydrobiopterin is a cofactor for phenylalanine hydroxylase (along with oxygen) that converts phe to tyr ~2% of infants

with inherited hnyperphenylalaninemia have a defect in the synthesis or recycling of the biopterin cofactor. All infants with

confirmed hyperphe should be tested for a biopterin defect by blood and urine pterin screening.

The correct answer is A.

Which of the following disorders is the most likely diagnosis in an infant with progressive liver failure, elevated serum

alpha-fetoprotein and succinylacetone in the urine?

A. 1-antitrypsin deficiency

B. hepatitis C

C. hepatorenal tyrosinemia

D. tyrosine aminotransferase deficiency

E. acetyl CoA-carboxylase deficiency

Hepatorenal tyrosinemia is also called tyrosinemia type I and results from a defect in last step of tyrosine degradation

fumarylacetoacetate hydrolase (FAH).


Intermittent treatment with metronidazole is recommended in patients with propionic academia or methylmalonic

acidemia for which of the following therapeutic effects?

A. gut flora produce substantial amounts of propionate

B. it promotes normal bowel function

C. it provides a source of reducing equivalents

D. it reduces the incidence of sepsis

E. reduction of enteric bacteria synthesis of valine and isoleucine

Metronidazole is an antibiotic used against anaerobic bacteria and protozoa. Some gut flora can generate propionate (which

can be converted to MMA). Thus, some doctors advocate using medtronidazole to reduce gut flora and propionate

production in PA or MMA.

The correct answer is A

Neonatal hypotonia, seizures, apnea and hiccups are features of which of the following inborn errors of metabolism?

A. citrullinemia

B. galactosemia

C. isovaleric acidemia

D. maple syrup urine disease

E. nonketotic hyperglycinemia

These are classic findings in nonketotic hyperglycinemia, particularly the seizures and hiccups, which may occur prenatally.


A six month old girl is referred for megaloblastic anemia. She is otherwise healthy and has been exclusively breast

fed. Metabolic screening reveals mildly elevated methylmalonic acid in her urine and a plasma total homocysteine

level of 27 uM (nl 5-8). The mother states that her older daughter, now age 3, who is the patient's maternal half-

sister, had similar anemia as an infant, but is "now fine." Which of the following assessments is the best course of

action in the evaluation of this patient?

A. Cobalamin complementation studies on the patient's fibroblasts

B. Measurement of serum B12 level and total homocysteine in the mother

C. Measurement of serum B12 level and total homocysteine in the sister

D. Measurement of transcobalamin II levels in the patient

E. Sequencing the methylmalonyl CoA mutase gene in the patient

This is likely a transient B12 deficiency in the patient and her sister secondary to B12 deficiency in the mother. The fact that

the sisters have different fathers makes a defect in cobalamin metabolism itself in the patient or her sister much less likely.

While transcobalamin II deficiency can produce megaloblastic anemia in infants (often with FTT and other sx), this is very rare

and is also an autosomal recessive disorder. The reason for B12 deficiency in the mother is often undiagnosed pernicious

anemia, but it can also occur in strict vegans.


Very long branch-chain fatty acids undergo -oxidation in which of the cellular organelles?

A. endoplasmic reticulum

B. Golgi apparatus

C. mitochondria

D. nuclear envelope

E. peroxisomes


Metabolic defects that cause Congenital Adrenal Hyperplasia usually involve which of the following enzyme

deficiencies?

A. Androgen receptor deficiency

B. Aromatase deficiency

C. Cholesterol desmolase deficiency

D. 5-α-Reductase deficiency.

E. 21-Hydroxylase deficiency

21-Hydroxylase deficiency causes ~95% of cases of CAH. Aromatase deficiency causes inability to synthesize estrogen and

affected females have ambiguous genetalia and primary amenorrhea.

5-• -Reductase deficiency converts testosterone into the more potent dihydrotestosterone. Affected males can have

pseudovaginal perineoscrotal hypospadias Androgen receptor deficiency causes androgen insensitivity and feminization of

affected males.


Thrombosis and strokes are a frequent complication of which one of the following diseases?

A. Congenital Adrenal Hyperplasia

B. Galactosemia

C. Homocystinuria

D. Medium Chain AcylCoA Dehydrogenase Deficiency

E. Phenylketonuria


Thromboembolic events cause the death of 50% of individuals affected by Homocystinuria by 20 yrs.

Which of the following NBS acylcarnitine profiles is most suggestive of MCAD deficiency?

A. Increased C3 and C4

B. Increased C5-OH

C. Increased C6, C8 and C8/ C10 ratio

D. Increased C14-OH, C16-OH, C18-OH and C18:1-OH

E. Increased C14:1 and C14:1/ C12:1 ratio


Increased C6, C8 and C8/ C10 ratio is the profile for MCAD and

these are derived from medium chain fatty acids. Increased C14-OH, C16-OH, C18-OH and C18:1-OH is the profile for LCHAD

Deficiency. Increased C14:1 and C14:1/ C12:1 ratio is the profile for VLCAD deficiency. Increased C3 and C4 These are seen in

Propionic academia and SCAD deficiency, respectively.

A neonate, Sam, was referred for an elevated Gal-1-P and E Coli sepsis at 8 days of age. Sam is four-weeks-old and he

is on Prosobee (lactose free) formula. Which of the following laboratory tests is most likely to yield information that

will guide dietary recommendations for Sam?

A. A total galactose level in his blood

B,. A red blood cell galactose-1-phosphate level

C. A galactose-1-P uridyltransferase activity level

D. N1314D and -119GTCA deletion genotyping

E. Q188R genotyping

Sam's GPUT (GALT) enzyme level should clarify if he has classical galactosemia which is associated with both an elevated Gal-

1-P and E Coli sepsis. A. and B.— Since Sam may have been on a lactose free formula for several weeks his galactose and

galactose-1-phosphate levels are likely normal and will not clarify if he has classical galactosemia. D. and E..— Determining if

he has Duarte (N1314D and -119GTCA deletion) or Gal (Q188R) genotypes alone would only clarify dietary recommentations

for Sam if he should he be found to be homozygous for the Q188R mutation.


Sarah is a five-week-old girl who is brought to clinic by her foster parents. She is on regular formula. Her foster

parents just received Sarah's newborn screening results that show Sarah had phenylalanine levels of 660 and 1220

μmol/L at 3 and 32 days of age, respectively. After obtaining plasma amino acids, which of the following interventions

is the best management plan in this situation?

A. Start Sarah on a phenylalanine-free formula

B. Start Sarah on large neutral amino acids

C. Start Sarah on PEGylated phenylalanine ammonium lyase injections

D. Obtain urine pterins and start Sarah on a phenylalanine-free formula

E. Obtain urine pterins and start Sarah on tetrahydrobiopterin (Sapropterin)

Sarah's Phenylalanine level of 1220 μmol/L strongly suggests that she has Phenylketonuria (PKU). You should obtain a

confirmatory test (plasma amino acid levels of Phe & Tyr), exclude BH4 disorders (urine pterins) and start a Phe free formula

while waiting for the test results. A. Starting a Phenylalanine free formula doesn't exclude BH4 disorders. B. or C. Similarly

starting her on large neutral amino acids or PEGylated Phenylalanine Ammonium Lyase rather than a Phe

free formula are also not standard care. E. Starting her on BH4 (Sapropterin) at 20 mgm/kg/day rather than a Phe free

formula is not standard care.

The correct answer is D.

Your state Newborn Screening (NBS) Laboratory sends you a batch report of five abnormal NBS results on neonates

discharged from your facility two days ago. Which of the following abnormal NBS results warrants your immediate

attention for finding the patient and performing definitive

testing?

A. Biotinidase enzyme level was 1.2 times the normal cutoff

B. C6 and C8 levels were 1.2 times the normal cutoff

C. GALT enzyme level was 1.2 times the normal cutoff

D. Immunoreactive Trypsinogen level 0.8 times the normal cutoff

E. Phenylalanine level was 1.2 times the normal cutoff

C6 and C8 levels at 1.2 times the normal cutoffs suggests that the baby may have MCAD Deficiency which can cause lethal

hypoketotic hypoglycemia following fasting, gastroenteritis or poor feeding. This baby should be evaluated as soon as

possible, the NBS repeated, the parents be given instructions for what to do if the baby has poor feeding or lethargy, and

diagnostic tests for MCAD considered.

A. Increased biotinidase enzyme levels do not indicate biotinidase deficiency. C. Increased GALT enzyme levels do not indicate

galactosemia. D. Decreased Immunoreactive Trypsinogen levels do not indicate cystic fibrosis. E. A mildly increased Phe level

should be repeated but PKU is not a life-threatening disorder like MCAD.


Which ONE of the following is the most common mode of inheritance for inborn errors of metabolism?

A. Autosomal recessive

B. Autosomal dominant

C. X-linked

D. Mitochondrial (maternal)

E. Sporadic

A

Which ONE of the following is the most common mode of inheritance for mitochondrial disorders?

A. Autosomal recessive

B. Autosomal dominant

C. X-linked

D. Mitochondrial (maternal)

E. Sporadic

A

Which of the following disorders is characterized by the biochemical finding: high ammonia?

A. Lesch-Nyhan disease

B. Acute intermittent porphyria

C. X-linked adrenoleukodystrophy

D. Smith-Lemli-Opitz syndrome

E. Ornithine transcarbamylase (OTC) deficiency

E

Which ONE of the following is not typical of the presentation of an organic acidemia (e.g., propionic acidemia,

methylmalonic acidemia)?

A. Coma

B. Metabolic acidosis

C. Nausea and vomiting

D. Liver failure

E. High ammonia levels (hyperammonemia)

D

Which ONE of the following disorders/groups of disorders is not part of "expanded newborn screening" by tandem-

mass spectrometry?

A. Amino acid disorders

B. Lysosomal storage diseases

C. Organic acidemias

D. Galactosemia

E. Fatty acid oxidation defects

B

Which ONE of the following disorders does not generally show liver disease as a presenting symptom?

A. Galactosemia

B. Homocystinuria

C. Tyrosinemia type I

D. Alpha-1-antitrypsin deficiency

E. Neonatal hemochromatosis

B

Which ONE of the following statements about metabolic disease is true?

A. The clinical features in metabolic diseases are due only to the accumulation of precursor substrate

B. The phenotype of a metabolic disease is generally constant regardless of the age of onset

C. Malformations can occur in metabolic disease when the onset of disease occurs prenatally

D. Most mitochondrial diseases are inherited by maternal (mitochondrial) inheritance

E. The onset of dietary therapy for PKU once symptoms have begun offers no benefit to the patient

C

Which of the following disorders is characterized by the clinical feature: cataracts?

A. Cystinuria

B. Hunter syndrome

C. Krabbe disease

D. Gaucher disease

E. Galactosemia

E

Which of the following is the most appropriate treatment for Biotinidase deficiency?

A. Enzyme replacement therapy

B. Bone marrow transplantation

C. Sodium benzoate & phenylacetate

D. Vitamin supplementation

E. Regular feedings

D

Most metabolic disorders are not associated with a predisposition to sepsis or infection. Which ONE of the following

diseases is associated with an increased risk of infection?

A. Tyrosinemia

B. Galactosemia

C. Medium chain acyl CoA dehydrogenase deficiency

D. Metachromatic leukodystrophy

E. Cystinuria

B

Which ONE the following acid-base scenarios is classically associated with the higher ammonia levels that occur in

patients with urea cycle disorders?

A. Primary metabolic acidosis

B. Primary metabolic alkalosis

C. Primary respiratory acidosis

D. Primary respiratory alkalosis

D. This is characteristic of urea cycle disorders.

Measurement of ammonia can be helpful as a diagnostic test in considering all the following groups of metabolic

diseases but one. Which ONE disease group is not associated with an abnormal ammonia level?

A. Organic acidemias

B. Urea cycle disorders

C. Mitochondrial disease

D. Fatty acid oxidation defects

E. Lysosomal storage diseases

E

Trichorrhexis nodosa (or "kinky hair") is an abnormal hair finding seen in patients with Menkes disease. Which ONE of

the following diseases is also associated with this clinical feature?

A. Homocystinuria

B. Methylmalonic academia

C. Hereditary fructose intolerance

D. Niemann-Pick disease

E. Argininosuccinic aciduria

E

Choose the most appropriate clinical feature associated with Homocystinuria.

A. Pulmonary embolism

B. Episodic pain

C. Renal Fanconi syndrome

D. Cardiomyopathy

E. Aversion to certain foods

A

Quizlet-inborn errors

Health & Medicine

Transcript of Quizlet-inborn errors