1. Amino acid disorders

3. Phenylketonuria (PKU)
Enzyme defect: phenylalanine hydroxylase (12th chromosome): more than 400 mutations
Incidence: Average 1:10,000 (Highest incidence in Turkey, 1: 4,000)

4. Phenylketonuria (PKU): Variants
1. Classical phenylketonuria (complete or near complete enzyme deficiency): phenylalanine levels above 20 mg/dL (<1200 mmol/L) require diet therapy
Atypical phenylketonuria (partial enzyme deficiency): (enzyme activity %1-5) require partial diet therapy
Benign phenylketonuria. phenylalanine levels below: 10 mg/dL (<600 mmol/L) no clinical findings, not requiring diet therapy
3. Malign phenylketonuria: Tetrahydrobiopterin (BH4=cofactor of phenylalanine hydroxylase): Severe neurologic findings, does not respond diet therapy. Dopamine and setotonin may be helpful.

5. Phenylketonuria (PKU): Clinical findings
Severe brain damage, progressive motor-mental retardation
Spasticity
Paralysis
Convulsions
Self-mutilation
Light colored skin and eye (yellow hair, blue eyes; tyrosine deficiency)
Mouse-like odor in urine and sweat.

7. Phenylketonuria: Diagnosis
High phenylalanine (N: <2mg/dL) and low tyrosine (N: <2mg/dL) levels,
Ferric chloride test gives green color in urine (not reliable).
Neonatal screening: Guthrie-card (taken between 3rd and 7th days of life)

8. Phenylketonuria:Therapy
Phenylalanine restricted diet, supplementation of tyrosine, essential amino acids and trace elements.
Goals of the therapy:
0-10 years: phenylalanine values: mg/dL
11-16 years: phenylalanine values: <15 mg/dL
16+ years: phenylalanine values: <20 mg/dL
Pregnant mothers with PKU: phenylalanine values < 7mg/dL
Prognosis: with immediate and efficient treatment, normal development and intelligence

9. Maternal PKU= phenylketonuric fetopathy
Normal phenylalanine levels
Microcephaly
Cardiac defects
Motor-mental retardation
No therapy

11. Tyrosinemia Type I Enzyme defect: Fumarylacetoacetate hydroxylase
Clinical findings
Acute infantile form: Severe liver failure, vomiting, bleeds, sepsis, hypoglycemia, renal tubulopathy (Fanconi syndrome)
Chronic form: Hepatomegaly, cirrhosis, growth retardation, rickets, hematoma, tubulopathy, neuropathy, and abdominal pain (due to porphyrines)

12. Tyrosinemia Type I: Diagnosis
High succinylacetone levels (diagnostic). tyrosine levels: normal or slightly elevated.
Methionine: high
Delta-aminolevulinic acid: high (colic)
Alfa-feto protein: very high (marker of hepatocellular carcinoma)

13. Tyrosinemia Type I: Therapy
NTBC 1 mg/kg: blocks the accumulation of toxic metabolites (succinylacetone); beware tyrosine elevation and give tyrosine-restricted diet
If this therapy fails consider liver transplantation.

14. Tyrosinemia Type I: Complications
Renal failure
Hepatocellular carcinoma (monitor alfa-feto protein), check periodically liver ultrasongraphy and biopsy.
Prognosis: Relatively good under NTBC treatment.

16. Tyrosinemia Type II Enzyme defect: Cytosolic tyrosine aminotransferase
Clinical findings: Painful corneal lesions (lacrimation, photophobia, scars), mild mental retardation
Diagnosis: High tyrosine and phenylalanine levels
Therapy: Tyrosine and phenylalanine-restricted diet

18. Alcaptonuria Enzyme defect: Homogentisate oxygenase
Clinical findings: black discoloration in urine at acid pH; mild arthritis in adults
Diagnosis: High homogentisic acid levels in urine
Therapy: Protein-restricted diet? NTBC?
Prognosis: Relatively good without treatment

19. Methionine metabolism

20. CLASSICAL HOMOCYSTINURIA
Enzyme defect: Cystationine-ß-synthase
Mechanism: Accumulation of homocysteine (collagen disorder)
Clinical findings: Progressive disease, usually starting with school age. Marfan-like appearance (archnodactyly), progressive myopia (the earliest finding), lens dislocation, epilepsy, mental retardation, osteoporosis, thromboembolism !!!

21. Marfan syndrom

22. HOMOCYSTINURIA
Diagnosis: High methionine, high homocysteine (N: µmol/L) and low cysteine levels. Positive nitroprusside test in fresh urine
Therapy: Pyridoxine (Vit. B6): mg/day + folic acid 10 mg/day.
If this fails diet + betaine (100 mg/kg) up to 3X3 g
Goal: Keep homocysteine <30µmol/L.

23. MILD HYPERHOMOCYSTEINEMIA Causes
Methylene tetrahydrofolate reductase (MTHFR) polymorphism, thermolabile variant, homozygosity, up to 5% in Europeans, 60% in Asiasns
Heterozygosity for cystationine-ß-synthase
Endogenous and exogenous disorders of folic acid metabolism
Vitamin B12 deficiency

24. MILD HYPERHOMOCYSTEINEMIA
Clinical findings:
Premature vascular disease in the 3rd and 4th decade (infarctions, thrombosis embolies)
Maternal hyperhomocysteinemia: congenital defects
Neural tube defects
Cardiac output defects
Renal defects
Pyloric stenosis?

26. Maple syrup urine disease
Enzyme: Branched-chain alfa-ketoacid dehydrogenase complex
Incidence: 1:200,000, autosomal recessive
Clinical findings
Severe form: Progressive encephalopathy, cerebral edema, lethargy, coma after the 3rd day of life, “çemen” odor in urine and sweat
Mild form: Developmental retardation, recurrent ketoacidotic decompensation

27. Diagnosis:
“Çemen” odor in urine and sweat, positive DNPH test in urine (non-spesific),
Aminoacid analysis: high valine, leucine, isoleucine and alloisoleucine (diagnostic) levels.
Therapy:
Acute: Detoxification (dialysis, exchange transfusion)
Augmentation of anabolism : Glucose + insulin
Chronic: Diet (monitor leucine level) ± vitamin B1 (thiamin): 5 mg/kg/day

28. Disorders of amino acid transport

29. Methionine Malabsorption
Methionine malabsorption in renal tubules and intestines.
Clinical findings: White hair, convulsions,, diarrhea, edema , mental retardation, odor (like beer).
Therapy: Diet deficient in methionine.

30. HARTNUP DISEASE
Defect: Intestinal and renal tubular reabsorption defect of the neutral amino acids (alanine, valine, threonine, leucine, isoleucine, phenylalanine, tyrosine, tryptophan, histidine, glycine; tryptophan deficiency leads nicotinic acid and serotonine deficiency.
Clinical finding: Photodermatitis, cerebellar ataxia; often asymptomatic
Diagnosis: High levels of neutral amino acids in urine low levels of neutral amino acids in plasma.
Therapy: Nicotinamide mg/day, sun protection

32. LYSINURIC PROTEIN INTOLERANCE
Defect: Intestinal and renal tubular reabsorption defect of the dibasic amino acids (lysine, arginine and ornithine) lead blockage of urea cycle; lysine deficiency
Clinical findings: Intestinal protein intolerance, failure to thrive, osteoporosis, and hyperammonemia with progressive encephalopathy
Diagnosis: Hyperammonemia, low lysine, arginine and ornithine in plasma, high LDH levels.
Therapy: Citrulline substitution, protein restriction

33. CYSTINURIA
Defect: Renal tubular reabsorption defect of the dibasic amino acids (lysine, arginine, ornithine and cystine)
Clinical findings: Neprolithiasis (cystine crystallizes above 1250 µmol/L at pH 7.5)
Diagnosis: Positive nitroprusside test in urine, increased levels of acids lysine, arginine, ornithine and cystine in urine, plasma levels are generally normal.
Therapy: High (>5L) fluid intake, alkalisation of the urine (urinary infections!). Consider penisillamine (1-2 g/day), mercaptopropionylglycine or captopril in selected cases.

34. ORGANIC ACIDEMIAS Pahogenesis
Mitochondrial accumulation of related CoA-metabolites
Clinical findings
Acute neonatal form
Lethargy * Coma
Feeding problems * Hypotonia/hypertonia
Myoclonic jerks * Cerebral edema
Dehydration * Unusual odor

35. ORGANIC ACIDEMIAS: Forms
Acute intermittent form
Recurrent episodes of acidotic coma
Ataxia
Focal neurologic signs
Chronic progressive form
Failure to thrive, Anorexia
Chronic vomiting
Hypotonia
Developmental retardation

36. ORGANIC ACIDEMIAS Laboratory findings Acidosis (increased anion gap)
Hyperammonemia
Hyperlactatemia
Diagnosis
Organic acids in urine (GC-MS)
Enzyme and DNA studies

37. ORGANIC ACIDEMIAS:Therapy
Acute
Remove toxins: dialysis, hemofiltration and exchange transfusion
Interrupt catabolic state
Stop protein intake
Give carnitine ( mg/kg)
Long term
Protein restricted diet (special formulas if available)
Carnitine
Vitamins (Vit. B12, Vit. B1, Vit. B2, biotin)

38. Features of some organic acidemias
Izovaleric acidemia
Ketoacidosis, dehydration, neutropenia, thromboscytopenia, hyperammonemia, sweety feet odor
Propionic acidemia
Motor-mental retardation, ketoacidosis, dehydration, neutropenia, thromboscytopenia, hyperammonemia, hipoglycemia
Methylmalonic acidemia
Motor-mental retardation, ketoacidosis, neutropenia, thromboscytopenia, hyperammonemia, hypoglycemia, response to vit B12 (+)

39. Biotinidase deficiency
Biotin (complex)
Biotinidase
Biotin (free)
piruvate carboxylase
asetyl CoA carboxylase
propionyl CoA carboxylase
beta-methylcrotonyl CoA carboxylase

40. Biotinidase deficiency
Incidense
World. 1:60,000
Turkey: 1:10,000
Clinical and laboratory findings
Severe metabolic acidosis
Alopecia
Seborrheic skin eruptions
Refractory convulsions
Therapy 5-10 mg/day biotin (life long).

41. Urea cycle defects

42. Carbaglu (+)

43. Urea cycle defects Incidence: 1:10,000 (cumulative) Genetics
Ornitine transcarbabamylase deficiency (most common urea cycle defect, X-linked)
Argininosuccinate synthase deficiency (citrullinemia, (the second most common urea cycle defect, OR)
Carbamylphosphate synthase I deficiency (OR)
Argininosuccinate lyase deficiency (argininosuccinic aciduria, OR)
Arginase deficiency (argininemia, OR)

44. Urea cycle defects: Clinical findings
Main symptom (acute/or chronic encephalopathy) is related to high protein intake, increased catabolism, infections or stress
Neonates:
* Poor feeding * Temperature lability
* Lethargy * Hyperventilation (respiratory alkalosis)
* Loss of reflexes * Intracranial hemorrhages
* Seizures * Progressive encephalopathy
Infants and children
* Failure to thrive * Episodic encephalopathy
* Feeding problems * Ataxia
* Nausea, vomiting * Convulsions
Adolescents and adults
* Chronic neurologic symptoms * Episodic encephalopathy
* Chronic psychiatric symptoms * Behavioral problems

45. Urea cycle defects Laboratory findings
Hyperammonemia (generally >400 µmol/L in urea cycle defects)
Amino acids in serum
Organic acids in urine
Differential diagnosis
Organic acidurias:
Liver diseases: neonatal hepatitis, galactosemia, tyrosinemia, respiratory chain defects
Transient hyperammonemia of newborn due to patent ductus venosus.

46. CPS= Karbamoil fosfat sentaz OTC= Ornitin transkarbomoilaz ASA=Arjininosüksinik asit AS=Arjininosüksinat sentaz AL=Arjininosüksinat liaz(sitrüllinemi)

47. Urea cycle defects: Acute therapy
Stop protein intake
Interrupt catabolic state by high calorie infusion (carbohydrate + lipid)
Remove ammonia when >400 µmol/L by hemodiafiltration, hemofiltration, or hemodialysis, (periton dialysis is not effective)
Give arginine 350 mg/kg in order to support urea cycle.
Give sodium benzoate: 350mg/kg/day
Give sodium phenylbutyrate 250mg/kg/day
Aim for an ammonia concentration < 200µmol/L

48. Urea cycle defects Chronic therapy
Restriction of protein intake ( g/kg/day) +arginine +
sodium benzoate + sodium –phenylbutyrate
Prognosis
Poor if there is prolonged coma (>3 days), and symptoms and signs of increased intracranial pressure

49. Defects of Fatty acid oxidation

50. (acyl CoA dehydrogenases)
Fatty acid oxidation
Fatty acid (plasma)
Asetil CoA
Fatty acid (mitochondria)
Carnitine
Carnitine enzymes
Beta-oxidation
(acyl CoA dehydrogenases)
131 ATP
Keton bodies
HMG CoA- liase
HMG CoA- synthase
3-ketothiolase (tioforase)
Krebs cycle

51. Fatty acid oxidation

52. Disorders of fatty acid oxidation
During prolonged fasting mitochonrial oxidation of fatty acids provides up to 80% of the total energy requirement.

53. Fatty acid oxidation: Etiology
Carnitine transporter deficiency
Defects of carnitine cycle
Carnitine palmitoyltransferase I (CPTI) deficiency
Carnitine translocase deficiency
Carnitine palmitoyltransferase II (CPTII) deficiency
ß-oxidation defects
Very long-chain acyl-CoA dehydrogenase (VLCAD) deficiency
Medium-chain acyl-CoA dehydrogenase (MCAD) deficiency
Short-chain acyl-CoA dehydrogenase (SCAD) deficiency
Long-chain hydroxyacyl-CoA dehydrogenase (LCHAD) deficiency
Medium-chain hydroxyacyl-CoA dehydrogenase (LCHAD) deficiency
Short-chain hydroxyacyl-CoA dehydrogenase (LCHAD) deficiency

54. Fatty acid oxidation: Pathogenesis
Insufficient energy production during fasting
Deficiency of mitochondrial free CoA due to accumulation of toxic intermediary products

55. Clinical findings (Reyelike syndrome)
Life-threatening hypoketotic hypoglycemic coma during catabolic states (prolonged fasting, infections, operations)
Liver failure
Skeletal myopathy, cardiomyopathy

56. Fatty acid oxidation: Laboratory findings
Ketones: low, ammonia: high, glucose: low to normal, liver enzymes: high
Total carnitine: low (high in CPTI deficiency)
Acyl carnitine/total carnitine: Low
Dicarboxilic acids in urine (GS-MS)
Acylcarnitine profile (Diagnostic)
Enzyme studies (Fibroblasts, lymphocytes)

57. Fatty acid oxidation: therapy
Acute therapy
High dose glucose (7-10 mg/kg/min), no lipids (!)
Carnitine (100mg/kg): not in carnitine cylce defects, and in LCHAD deficiency
Chronic therapy
Avoid prolonged fasting, careful monitoring during catabolic states