Amino Acid Disorders

Question 1

Most common form of inheritance of amino acid disorders

Answer 1

Autosomal recessive

Question 2

Inheritance of ornithine transcarbamylas deficiency

Answer 2

X linked

Question 3

Inheritance of Menkes Kinky-Hair Disease

Answer 3

X linked

Question 4

Inheritance of a-galactosidase A deficiency (Fabry disease)

Answer 4

X linked

Question 5

Inheritance of Hypoxanthine-guanine phosphoriboxyl transferase deficiency (Lesch-Nyhan syndrome)

Answer 5

X linked

Question 6

Inheritance of Iduronate sulfatase deficiency (Mucopolysaccharidosis II/Hunter syndrome)

Answer 6

X linked

Question 7

Inheritance of glucose-6-phosphate dehydrogenase (G6PD) deficiency

Answer 7

X linked

Question 8

Inheritance of metachromatic leukodystrophy

Answer 8

X linked

Question 9

Inheritance of Type IX Glycogen Storage Disease (Phosphorylase B Kinase Deficiency)

Answer 9

X linked

Question 10

Inheritance of Acute Intermittent Porphyria

Answer 10

Autosomal dominant

Question 11

Inheritance of Acute Hepatic Porphyria

Answer 11

Autosomal dominant

Question 12

Inheritance of Porphyria cutanea tarda

Answer 12

Autosomal dominant

Question 13

Inheritance of porphyria varigata

Answer 13

Autosomal dominant

Question 14

Inheritance of Protoporphyria

Answer 14

Autosomal dominant

Question 15

Name 6 amino acid disorders

Answer 15

PKU
Tyrosinemia
Branched chain amino acid disorders
Homocystinuria
Non-ketotic hyperglycinemia
Cystinosis

Question 16

Deficient enzyme in PKU

Answer 16

Phenylalanine hydroxylase (PAH)

Question 17

Cause of 2% of PKU (not due to PAH deficiency)

Answer 17

Defect in tetrahydrobiopterin (BH4)

Question 18

PKU Incidence

Answer 18

1/15,000 caucasians

Question 19

PKU symptoms (untreated)

Answer 19

Intellectual disability, eczema, decreased skin pigmentation, seizures, autism

Question 20

How PKU is diagnosed on NBS

Answer 20

Serum PHE level >20MG%

Question 21

PKU treatment

Answer 21

Low Phe diet for life - watch out for maternal PKU

Question 22

Clinical signs of maternal PKU

Answer 22

Mental retardation, microcephaly, congenital heart disease, intrauterine growth retardation/low birth weight

Question 23

Name 3 defects in Branched chain amino acid metabolism (3 conditions)

Answer 23

Maple syrup urine disease
3-Methylcrotonyl-CoA Carboxylase Deficiency
3-Hydroxy-3-Methylglutaryl-CoA Lyase Deficiency

Question 24

MSUD incidence

Answer 24

1/100,000 to 1/300,000

Question 25

Types of MSUD

Answer 25

Classic infantile, intermittent, intermediate

Question 26

MSUD diagnosis

Answer 26

Elevated leucine
Elevated isoleucine
Elevated valine (all on serum amino acids)
ALLOISOLEUCINE PRESENT

Question 27

MSUD treatment

Answer 27

Dietary restriction of branched chain amino acids

Thiamine

Question 28

Population most frequently affected with MSUD

Answer 28

Mennonite

Question 29

Symptoms of Classic Infantile MSUD

Answer 29

Poor feeding, apnea, ketoacidosis, seizures, hypglycemia

Question 30

Symptoms of intermediate MSUD

Answer 30

Ataxia, failure to thrive, progressive

Question 31

Symptoms of intermittent MSUD

Answer 31

Intermittent ataxia and ketoacidosis during infection or protein ingestion, normal intervals

Question 32

Deficiency seen in classic homocystinuria

Answer 32

CBS deficiency (cystathionine B-Synthase)

Question 33

Symptoms of homocystinuria

Answer 33

Ectopia lentis, myopia, osteoporosis, codfish vertebrae, scoliosis, increased long bone length, irregular metaphses, metaphysical spicules, abnormal size/shape of epiphyses, growth arrest lines, pes cavus, high arched palate, mental retardation, psychiatric disturbances, vascular occlusions, malar flush, livedo reticularis, fair/brittle hair, thin skin, fatty changes in liver, inguinal hernia, myopathy, endocrine abnromalities, reduced clotting factors

Question 34

Homocystinuria incidence

Answer 34

1/200,000

Question 35

Main groups of symptoms of homocystinuria

Answer 35

Eye
skeletal
CNS
Vascular