“Neurotransmitter” Disorders

Simon.heales@gosh.nhs.uk

Chemical Neurotransmission

• Neurotransmitters –Substances that upon release from nerve terminals, act on receptor sites at post-synaptic membranes to produce either excitation or inhibition of the target cell

BH2

Tyrosine

Tryptophan

Phenylalanine

L-Dopa

5-HTP

Tyrosine

Dopamine

Serotonin

qBH2qBH2BH4

HVA

5-HIAAPLP

O2

BH4

GTP

Dihydroneopterin Triphosphate

6-Pyruvoyltetrahydropterin

Tetrahydrobiopterin

Dihydroneopterin

GTP cyclohydrolase

Pyruvoyl tetrahydroptein synthase

Aldose reductase /Sepiapterin reductase

P3

-VE

BH4 Salvage

Tyr L-Dopa

BH4BH4 qBH2qBH2DHPRDHPR

NADHNADHNADNAD++

PCD+

PCD = pterin PCD = pterin carbinolaminecarbinolamine dehydratasedehydrataseDHPR = DHPR = dihydropteridinedihydropteridine reductasereductase

BH2BH2

• Tube 1 0.5ml HVA & 5-HIAA

• Tube 2 0.5ml 5-MTHF

• Tube 3 1.0ml Pterins

CSF – Sample Requirements

(DTE/DETAPAC)

Collect at bedside and freeze immediately (not the form !)Collect at bedside and freeze immediately (not the form !)

58-220985.1- Adult

89-3671851.10 – 5.00

68-4512500.67 – 1.00

63-5032710.34 - 0.66

199-6084170 - 0.335-HIAA

71-5652815.1- Adult

154-8674651.10 – 5.00

176-8515080.67 – 1.00

362-9555870.34 - 0.66

324-10987140 - 0.33HVA

Range MeanAge (years)Metabolite

nmol/L

Pediatr Res (1993) 34, 10-14

7-6519ALLNH2

0.4-13.95.6ALLBH2

9-39235.1- Adult

8-57331.10 – 5.00

19-56380.67 – 1.00

23-55370.34 - 0.66

27-105670 - 0.33BH4

Range MeanAge (years)Metabolite

nmol/L

Pediatr Res (1993) 34, 10-14

BH4 Deficiency

• Decreased spontaneous movements, mental

retardation, convulsions, disturbances of tone

and posture, drowsiness, irritability, abnormal

movements, recurrent hyperthermia, hyper-

salivation, swallowing difficulties, diurnal

fluctuations of alertness, microcephaly

With HyperphenylalaninemiaGTP cyclohydrolase I (GTPCH) deficiency;

Phe = 90-1200 umol/L

6-Pyruvoyl-tetrahydropterin synthase (PTPS) deficiency;Phe = 240-2500 umol/L

Dihydropteridine reductase (DHPR) deficiency; Phe = 180-2500 umol/L

Pterin-4a-carbinolamine dehydratase (PCD) deficiency;Phe = 180-1200 umol/l

Without hyperphenylalaninemiaSepiapterin reductase deficiency (SR).

Dopa-responsive dystonia (DRD) due to GTPCH deficiency;

Disorders of BH4 metabolism

www.BH4.org

0

100

200

300

400

500

600

700

1.8 1.9

HVA5-HIAA

DHPR Deficiency – Response to Treatment

Age (Years)

nm

ol/L

GTP

Dihydroneopterin Triphosphate

6-Pyruvoyltetrahydropterin

Tetrahydrobiopterin

Sepiapterin Reductase Deficiency

Sepiapterin Reductase Deficiency

Sex; Male. Dob; 31/12/1987. Sample; 09/05/2003. Dystonia responsive to L-DOPA. No hyperphenylalaninaemia. DHPR normal.

HVA: 23 ((71- 565 nmol/L)

5-HIAA: 2 (58- 220 nmol/L)

BH4: 11 (9- 39 nmol/L)

BH2: 64 (0.4- 13.9 nmol/L)

Total Neopterin: 19 (7- 65 nmol/L)

GTP

Dihydroneopterin Triphosphate

6-Pyruvoyltetrahydropterin

TetrahydrobiopterinBH2DHFR -Liver

L-Dopa Responsive Dystonia

•Hereditary progressive dystonia (Segawa et al., 1971).

•Autosomal Dominant – Female predominance (4:1).

•GTP cyclohydrolase – a causitive gene (Ichinose et al., 1994)

Mutations in gene cause at least 2 disorders:-

AR – present within 6 months, hyperphenylalaninaemia& marked impaitment of dopamine and serotonin turnover.

AD - DRD. Residual activity 2-20%.

Phenylalanine Metabolism

GTP

BH4

p35

Phe Tyr

++veve --veve

GTP cyclohydrolase

Phenylalanine Loading TestPlasma Phenylalanine after 100mg/kg oral phenylalanine

0

200

400

600

800

1000

1200

0 1 2 3 4 5 6

Time (hrs)

Phe

(um

ol/L

)LLN Phe

ULN Phe

Phe

0

50

100

150

200

250

0 1 2 3 4 5 6

Time (hrs)

Tyr

(u

mo

l/L)

LLN Tyr

ULN Tyr

Tyr

0

2

4

6

8

10

12

0 1 2 3 4 5 6

Time (hrs)

Ph

e/T

yr r

atio LLN P/T ratio

ULN P/T ratio

P/T ratio

Phenylalanine load – DRD. DOB; 20/09/1966. Sample; 13/04/2004

Reported comment:‘Phe response slightly outside 95%CI and conversion to Tyr rather sluggish. These results do not exclude a pterin related defect.’

Low CSF neopterin,BH4, HVA and 5-HIAA

Outcome:GTP cyclohydrolasedeficiency….

Other Neurotransmitter Disorders

•Tyrosine Hydroxylase Def.•“Increased Dopamine turnover”•Aromatic Amino Acid Decarboxyalse Def.

•Pyridoxal Phosphate Def.•5-Methyltetrahydrofolate Def.

Tyrosine Hydroxylase Deficiency

Tyr Dopa Dopamine HVA

• Parkinsonian, ptosis, drooling, myoclonic jerks, severe head lag and trunkal hypotonia.

• L-Dopa marked and sustained improvement in hypokinesia and parkinsonian symptoms.

• Identified from CSF analysis; Normal pterin & 5-HIAA concentration. Very low HVA. Mutation analysis also available.

Tyrosine Hydoxylase Deficiency

Sex; Male. Dob; 17/05/2007. Sample; 27/02/2008

HVA: <10 (154-867 nmol/L)

5-HIAA: 137 (68 -451 nmol/L)

BH4: 36 (19-56 nmol/L)

BH2: 8 (0.4-13.9 nmol/L)

Total Neopterin: 9 (7-65 nmol/L)

Serum Prolactin 706 (86 – 324 mU/ml)

Tyrosine Hydroxylase Deficiency

Tyr Dopa Dopamine HVA

HVA: <10 (154-867 nmol/L)

Patient image has been removed

Tyrosine Hydroxylase Deficiency

Tyr Dopa Dopamine HVA

L-DOPA

Patient image has been removed

Increased Dopamine Turnover

First female child of consanguineous parents. 36 week gestation.Feeding difficulties from birth. 6 months reduced movements and failure to achieve milestones. 9 months able to smile but general paucity of movements. Rigidity of all limbs suggestive of dopamine deficiency. Left convergent squint but no abnormal eye movements detected.

HVA: 1705 ((154–867 nmol/L)

5-HIAA: 250 (89-367 nmol/L)

Pterin profile and 5-MTHF status unremarkable

Elevated urinary HVA

Serum Prolactin; 915 (<500 mU/ml)

Aromatic Amino Acid Decarboxylase Deficiency

Tyr L-Dopa Dopamine HVA

Trp 5-HTP Serotonin 5-HIAA

Clinical features resemble those of recessive BH4 deficiency; hypotonia, occulogyric crises, ptosis and paucity of spontaneous movement. Can be fatal

Urine: Vanillactic acid

CSF: Low HVA + 5Low HVA + 5--HIAA, but HIAA, but normalnormal pterin profile and accumulation pterin profile and accumulation of of 33--OO--methyldopamethyldopa. Enzymatic analysis possible on plasma.. Enzymatic analysis possible on plasma.

Treatment;Treatment; B6, MAOI & dopamine agonists.

PLP

Tyrosine

Tryptophan

L-Dopa

5-HTP

Dopamine

SerotoninBH4

HVA

5-HIAAPLP

AADC

3-Methyldopa

Vanillactic acid

Aromatic Amino Acid DecarboxylaseDeficiency

Male. Dob; 28/08/2007.Sample; 10/01/2008

Floppy, episodes of dystonia, developmental delay

HVA 47 (362-955 nmol/L)5-HIAA 14 (63- 503 nmol/L)3-Methyldopa 1170 (<300 nmol/L)PLP 32 (23-87 nmol/L)

Plasma AADC Activity 0.7 (36 -129 pmol/min/ml)

Serum Prolactin 900 (85 – 250 mU/ml)

Tyrosine

Tryptophan

L-Dopa

5-HTP

Dopamine

SerotoninBH4

HVA

5-HIAAPLP

AADC

3-Methyldopa

Vanillactic acid

Vitamin B6 Metabolism

Pyridoxine-5’- phosphate Pyridoxamine-5’- phosphate

Pyridoxal-5’- phosphate

N

CH2OH

HO

H3C

CH2OPO3H2

CH2OPO3H2

CH2OPO3H2

N

CH2NH2

HO

H3C

N

CHO

HO

H3C

PNPOPNPO

PNPO = Pyridox(am)ine-5’-oxidase

PNPO Deficiency

• Neonatal epileptic encephalopathy

•• Fetal distress, prenatal seizures, low Apgar

•• Pseudo AADC deficiency – Not consistent

•• Glycine & Threonine – Not consistent

• Vanillactate excretion – Consistent ?

PNPO Deficiency

CSF (PLP)CSF (PLP)

0

10

20

30

40

50

60

70

80

90

100

0 2 4 6 8 10 12 14 16Age (Years)

PLP

(nm

ol/L

)

CSF 5-MTHF Deficiency

• DHPR deficiency• MTHFR deficiency• AADC deficiency• 3-Phosphoglycerate dehydrogenase def• Rett syndrome• Aicardi Goutieres• Mitochondrial disorders • L-dopa treatment• Methotrexate• Anticonvulsants• Steroids• Co-trimoxazole

Cerebral Folate Deficiency - Neurological syndrome associated with low CSF 5-MTHF and normal peripheral folate.

Cerebral Folate Deficiency

•Presentation 4 – 6 months after birth with irritability and sleep disturbance

•Deceleration of head growth (6 – 18 months)•Psychomotor retardation, sometimes followed

by regression.•Cerebellar ataxia•Pyramidal tract signs in lower limbs•Dyskinesis•Epileptic seizures

•Sub group – autistic features

Cerebral Folate Deficiency•Production of blocking auto-antibodiesagainst folate receptor ?? Produced by exposure to soluble folate binding proteins in human or bovine milk ?? (Ramekers et al., 2005).

•Milk free diet down regulates folatereceptor auto-immunity (Ramekers et al., 2008).

•Blocking auto-antibodies not present in allpatients with cerebral folate deficiency.

N

N

N

NH

NH2

NH

O

NH

O OH

OH

O

OH CH3

5-Methyltetrahydrofolate

•CSF deficiency documented in mitochondrial disorders

•Responsive to folinic acid

•25% of ETC defects associated with CSF 5-MTHF deficiency

•No apparent correlation with magnitude of defect

5MTHFEndocytosis

Folate PolyglutamatePool

5MTHFFR1

RFC

sFR1

-ve

PLASMA CSF

1 2

O2

._5MTHF ???

CSF 5-MTHF Deficiency & Mitochondrial Disorders

5-MTHF

F. 15 yrs 29 (46 - 160 nmol/L)M. 9 yrs 5 (72 – 172 nmol/L)M. 8 yrs 44 (72 – 172 nmol/L)F. 2 yrs 17 (52 - 178 nmol/L)F. 6 yrs 7 (72 – 172 nmol/L)

•Leads to brain specific folate deficiency

•Loss of function mutations in the FOLR1.

•Gene coding for the FR

•AR disorder manifests in late infancy with Severe developmental regression, movement disturbances,epilepsy and leukodystrophy

•Beneficial effect of folinic acid.

CSF 5-Methyltetrahydrofolate

•DHPR deficiency

•Long term L-dopa administration

L-DOPA 3-Methyldopa

Dopamine

COMT

10 year old female

GTP cyclohydrolase deficiency

62 (72-172 nmol/L)

Secondary Causes

• Hypoxia• Neurodegeneration• Epilepsy• Gaucher Disease• Mitochondrial Disease • Drugs• Sample Processing