2nd Cycle - 2nd IPNA ESPN MASTER for JUNIOR CLASSES

CYSTINOSIS

Prof. Dr. Rezan Topaloglu Hacettepe University Faculty of Medicine

Department of Pediatric NephrologyAnkara Turkey

• It is an autosomal recessive disease

• Characterized by accumulation of cystine due to defective cystine transport

CYSTEINE CYSTEINE

CYSTINE

Cystinosis

CTNS gene structure

2

Cytoplasm

Lysosomalmembrane

Lysosome

N-terminus

C-terminus

GY-DQ-LCTNS product Cystinosin predicted structure

367 aa

YFPQA

Mutations in CTNS gene

• More than 110 mutations have been reported

• Big deletion 57 kb

• Small deletions (13kb, 4 kb deletions)

• Insertions

• Missense or nonsense mutations

• Splicing mutations

• Partial replication of exon 9, a skipping of exon 5 (85 bp)

• The most common variant in North America and Nort Europe is 57 kb deletion Town et al 1998

• In Turkey and in neighboring no 57kb deletion but most common allele is c.681G>A (p.Glu227Glu) Topaloglu et al 2012 and 2017

•The size of this deletion was determined to be 57 kb

•57kb deletion that covers the first 9 exons and introns and intrups exon 10

•57 kb deletion extends into CARKL and TRPV1 gene causing more complex phenotypes

•76 % of patients European origin have this deletion either in heterozygous or homozygous state

•In the US and Northren European populations 50 % of nephropathic cystinosis is homozygous for this deletion

57 Kb deletion

Town M et al .Am J Hum Genet 1998;63:1352-1362

Topaloglu R et al. Pediatr Nephrol 2012; 27:115 & cJASN 2017 doi: 10.2215/CJN.00180117

Normal PTC and Lysosome Cystinotic PTC Cystinotic Lysosome

Festa PF et al. Nature Review Nephrology 2017;13:115-131

PATHOGENESIS of CYSTINOSIS

Cystinosis

• Rare autosomal recessive disorder estimated incidence 1/ 150.000 or 200.000 live births

• Lysosomal storage disease

Types• Classical, Infantile, Nephropathic cystinosis

• Late onset cystinosis Juvenile or Intermediate form often does not present with Fanconi syndrome may progress to ESRD within a few years of diagnosis

• Ocular non nephropatic form Adult or Bening form presents with photophobia

Clinical Findings of Nephropatic Cystinosis According to Age

Age Presentation

Birth Normal

Infancy Renal Fanconi syndrome-Dehydration, polyuria, polydipsia-Metabolic acidosis-Hypokalemi-Hypophosphatemia-Hypocalcemic tetany

Growth retardationVomitingRickets

Early childhood Photophobia

Pre-adolescence Renal failureRenal osteodystrophyHypothyroidism

Nesterova G et al. Pediatr Nephrol 2008;28:863

Gradual development of Fanconi syndrome in cystinosis

age (months)

1 2 3 4 5 6 7 8

ren

alsym

pto

ms

aminoaciduria

glucosuria

phosphaturia

renal bicarbonate loss

full-blown Fanconi

syndrome

Levtchenko E et al.Acta Pediatr 2006; 95:379

Topaloglu R et al.cJASN 2017 doi: 10.2215/CJN.00180117

Diagnosis

• Suspected clinical presentation

• The diagnosis can be confirmed by

• Measurement of leukocyte cystine levels • Controls < 0.3 nmol ½ cystine/mg protein

• Heterozygotes < 1 nmol ½ cystine/mg protein

• Patients at diagnosis > 2 nmol ½ cystine/mg protein

• Patients on cysteamine therapy < 1 nmol ½ cystine/mg protein

• Demonstration of corneal cystine crystals by the slit lamp exam > 1 year of age

• genetic analysis of the CTNS gene

Renal Disease

Kidney is main affected organ

Main Predictor of prognosis

Cystinosis presents with renal Fanconi Syndrome & it is the most common cause of renal Fanconi syndrome

Clinical Features

• Failure to thrive/growth retardation

• Polydipsia, polyuria

• Vomiting

• Constipation

• Dehydration

• Rickets

• Developmental delay/hypotony

Lab. FeaturespRTAPolyuriaAminoaciduriaGlucosuriaPhosphaturiaNa+, K+ , HCO3- losses HypercalciuriaLow molecular weight proteinuria, albuminuriaHyperuricosuriaCarnitinuria

Renal Pathology

• Typical swan neck deformity of proximal convulated tubules seen at 6 monts

• Other typical features: irregularities of proximal tubular cells (flat cells without brush boarder and large cells with hyperchromatic cytoplasm)

• giant multinucleated podocytes

• Podocyte detachment and progressive glomerular dysfunction and proteinuria in cystinosis

• Cystine crystals located in the lysosomes or in cytoplasm seen within interstitial cells rarely within podocytes

• Late stage Progressive tubulo-interstitial lesions interstitial fibrosis, tubular atrophy NEJM 2002 ; 347:111

Am J Kidney Dis 2008;51:893 KI 2008; 73:782

Glomerulus with multiple

multinucleated podocytes and parietal

epithelial cells (HE).

Interstitial cells display

cytoplasmic crystalline

inclusions (toluidine bluestain)

Interstitial cells containing multiple

clear, elongated, needle-shaped and

rhomboid cytoplasmic

inclusions(EM )

Renal functions

• In infancy or early childhood serum Cr is generally not elevated

• In the absence of Rx creatinin clearance decreases

• Among 205 European patients before cystiamine threapy end Stage renal failure developed at mean age 9.2 years

Gahl W. A. et al. N Engl J Med 2002;347:111-121

Renal Functions in untreated versus treated patients

.

Extra Renal involvement

Nesterova G et al. Pediatr Nephrol 2008;28:863

Extra-renal involvement

Eye• photophobia 50% 8-12 years • retinal blindness 10-15% 13-40 years

Endocrine organs• Growth retardation• hypothyroidism 50% 5-10 years• diabetes mellitus 5% 18-40 years• male hypogonadism 70% 18-40 years

Neuromuscular disease• myopathy 20% 12-40 years

Neurological complaints 2-10% 21-40 years• Epilepsy mental deterioration• cerebella and pyramidal signs• stroke-like episodes

Eye Involvement

Pigmentary retinopathy – impaired color vision and impaired night visionBand keratopathy which can impair vision

corneal cyristals

TR-6

Presented at age 1 year due to recurrent pneumonia and polyuria polydipsia failure to thrive Corneal

cystine cyristals were detected very good compliance to cysteamine

Homozygous for a new missense mutation in exon 8, p.Y173C

Cystine Cyristals

In vivo confocal microscopy

Bone Marrow aspiration increased proportion of macrophages containing polygonal cystine crystals 20% (Normal range 2-5%)

N Engl J Med 2015;373:e27.

Topaloglu R et al Minerva Pediatr 2014;66:123-130

GI Complications

• Untreated or undertreated patients develop GI symptoms in 2nd

or 3rd decade of life

• Spectrum of involvement diverse

• 77% have feeding abnormalities- reflux, dysmotility, pseudo obstruction, swallowing dysfunction

• Mild hepatomegaly , portal hypertension

• Exocrine pancreatic insufficiency

• Inflammatory bowel disease

CNS involvement in children 2-10%

• Intra cranial pressure may increase due to cystine deposition

• Pseudotumor cerebri

• CSF normal except elevetad intracranial pressure

• In some cases acetazolamide is enough in some ventriculo peritoneal shunt is needed

• Convulsions, spasticity

• Some have abnormal EEG without seizures

• Low visual memory may be related to cortical atrophy

• Phyco social difficulties

Treatment

• Treatment of Fanconi Syndrome-Symptomatic

• Treatment of cystine accumulation-Cystine depleting treatment- Specific

• Treatment of corneal depositions - Topical eye drops -Specific

Symptomatic Treatment for Fanconi syndromeThis treatment may delay kidney failure and improve growth

• Provide large amounts of water and sufficient food

• Nasogastric tube or gastrostomy in infants

• Potassium(KCL or K citrate)

• Sodium (bicarbonate or citrate) , in 3-4 doses

• Phosphate supplement, serum phosphate level = 3-3.5mg/dl (NaK Phosphate or phosphate Sandoz tbs P 16 mmol ) 0.5 mmol/kg/dose 2-3 times a day

• Ca supplementation

• 1α OH D3 to cure rickets 0.5-1.5 µg/d

to prevent rickets 0.1-0.3 µg/d

• Carnitine supplementation 50-100mg/kg/day ? Monitor plasma concentration and profile

• Indomethasine -effects on polyuria & electrolyte supplement Starting age usually 9 months dose: 0.5-1 mg/kg/day in 2 doses

• Avoid use with ACEi• Close monitoring kidney functions• Pay attention to GI disturbences

Specific Treatment CYSTEAMINEDepletes Intra-cellular Cystine Accumulation

LYSOSOM

CYSTINE

CYSTEIN

TRANSPOPTER

LYSINE

TRANSPOPTER

CYSTEAMINE

CYSTEIN CYSTEIN

Courtesy of Dr. Salih Kavukcu

Imideate Release Cysteamine bitartratecapsules : 50 mg or 150 mg

1.30-1.90 g/m²/day, in 4 doses

• Starting dose : 1/4 to 1/6 of scheduled maintenance dose, increased weeklyover 4-6 weeks to avoid nausea & vomiting

• Administration should be in 4 doses every 6 hours

• Adjust dose to maintain leukocytes cystine at kept <1 nmol 1/2 cystine/mg protein

• At adolescence and adult age 2.0 g/day recommended

• Maximum dose 1.90 g/m²/day

33

Cys

team

ine

con

cen

trat

ion

(m

g/L

)

WB

C C

ysti

ne

leve

l(n

mo

l ½ c

ysti

ne/

mg

pro

tein

)

Time (min)

Langman et al. cJASN 2012;7:1112

Delayed or slow -release cysteamine (RP103)

• WBC lowering effect: non-inferiority of RP103 compared to Cystagon

• Decreased use of PPI• 80% of initial Cystagon

dose

Short-term study

Long term study with slow release cysteamine

Long term -24 months study 2 studies

• Sustained WBC lowering effect• Stable eGFR• Improvement in social function, school function, and in

total function scores on the Pediatric Quality of Life

Langman et al. J Pediatr 2014;165:528Ahlenstiel Grunow T et al. Pediatr Nephrol 2016;

Adequate treatment with cystine depleting agent

• Significantly reduces the rate of progression to ESRF

• Improves growth retardation

• Postpones even prevents the extrarenal complications

hypothyroidism,

myopathy

pulmonary dysfunction,

DM

• Systemic cysteamine does not prevent corneal cysteine crystals , topical cysteamine eye drops are needed

Kleta R J Pediatr 2004;145:555

Growth curves of early and well-treated siblings with cystinosis

Cysteamin treatment initiated at age <2 versus > 2 years old p=0.02

Missense versus deletion/duplicatiom/splice mutations p=0.79

Most common mutations versus others p=0.54

Topaloglu R et al.cJASN 2017 doi: 10.2215/CJN.00180117

Brodin-Sartorius A; et all KI 2012;81:189

Monitoring the treatment and follow up of the patients

• Leukocyte cystine levels is key player

• Adjust dose to maintain leukocytes cystine at less than 1 nmol 1/2 cystine / mg protein

• Follow up should be multi disciplinary

• For children follow up every 3 month

• For adults follow up yearly or 2 times in a year

Cysteamine adverse effects

• Nausea - vomiting• Abdominal pain• Bad odour and taste• Headache, asthenia• Anorexia• Dyspepsia- PPIs may be needed

Cysteamine Adverse effects

• Bruise like skin lesions on the elbows, skin sitriaand severe muscular and bone pain

• Histology: reactive hemangio endotheliomatosis-increased survival of dermal microvascularendothelial cells due to cysteamine

• Collagen fiber abnormalities - synergistic effectof cysteamine and copper deficiency on inhibition of collagen cross linking (copperdeficiency was found in all patients with this sideeffect)

• Regression after decrease of doses may be seen• This side effect is found to be related with high

dose cysteamine . It is advise to use body surface area for dosing 1.3-1.95 g/m2/day

Besouw MT et al.

Renal transplantation in cystinosis

• No recurrence of cystinosis in renal graft

• graft biopsies: cystine crystals in invading host cells, but not in tubular or glomerular epithelium

• Living-related transplantation with heterozygote parent’s kidney is allowed

Renal graft survival

Van Stralen KJJ et al. CJASN 2011;6: 2485

Summary

• Early diagnosis and adequate treatment is the key factor• For early diagnosis think about cystinosis in patients with

failure to thrive, polyuria, polydipsia, hypophosphatemicrickets, glucosuria, proteinuria, photophobia, RF

• Cystine depleting treatment improves renal and extra-renal prognosis & should be administered as early as possible & should be continued life-long (also after renal transplantation)

• The administration of the higher than recommended doses of cysteamine should be avoided

• Ongoing research on new treatment modalities will improve the future of patients with cystinosis

Questions

•How one can suspect cystinosis in an infant ?

•What is cystinosin ?

•What is the most common endocrine complication in cystinosis

•Could the parents be donor ?

•How is the graft survival in cystinotic patients ?

THANK YOU

2nd Cycle 1st

IPNA -ESPN MASTER FOR JUNIOR CLASSES

2017 GLASGOW, UK

THANK YOU