Inborn Errors of Metabolism

Question 1

what happens in familial hypercholesterolaemia ?

Answer 1

• mutation on the Low Density Lipoprotein Receptor gene
• results in impaired LDL catabolism increasing plasma cholesterol.

*presents with Xanthomata

Question 2

what happens in familial hypertriglyceridaemia ?

Answer 2

• hepatic overproduction of VLDL
• reduced HDL cholesterol level
• reduced conversion of VLDL to LDL

Causes (1) obesity (2) increased alcohol consumption (3)

Question 3

IEM is classified based on intoxication effects into ;

Answer 3

1) Aminoacidopathies
2) Urea cycle defects
3) Organic acidemias
4) Disorders of carbohydrate metabolism

Question 4

IEM classified based on energy deficiency state into ;

Answer 4

• medium chain acyl CoA dehydrogenase deficiency
• very long chain acyl CoA dehydrogenase deficiency
• carnitine uptake effect
• glycogen storage disease

Question 5

IEM classified based on altered metabolism of complex molecules into ;

Answer 5

• lysosomal disorders
• peroxisomal disorders
• disorders of intercellular trafficking & processing

Question 6

common lab presentation of IEM

Answer 6

1) neonatal hypoglycemia
2) jaundice/icterus
3) metabolic acidosis
4) lactic acidosis
5) neonatal hyperammonaemia

Question 7

Diagnostic methods for prenatal diagnosis include

Answer 7

1) Chorionic volleys sampling (10-13wks)
2) Amniocentesis (14-20 wks)
3) DNA analysis

Question 8

newborn screening was originally for the detection of what ?

Answer 8

Phenylketonuria

Question 9

in sudden death _ is usually a common cause

Answer 9

FAO disorders

Question 10

what enzyme is deficient in phenylketonuria

Answer 10

phenylalanine hydroxyalse

Question 11

what causes Maple Syrup disease

Answer 11

• deficient carboxylation of leucine, isoleucine & valine
  -inactivity of thiamine pyrophosphate

Question 12

what enzyme is deficient in alkaptonuria

Answer 12

homogentisic acid oxidase

Question 13

most common urea cycle deficiency ?

Answer 13

ornithine transcarbamylase

*sex linked

Question 14

most common urea cycle deficiency ?

Answer 14

ornithine transcarbamylase

*sex linked

Question 15

other urea cycle deficient enzyme ;

Answer 15

carbamyl phosphate synthetase deficiency

Question 16

galactoseamia is due to deficiency of

Answer 16

Galactose-1-Phosphate Uridyl transferase

Question 17

GM1 gangliosidosis is due to deficiency of what enzyme ?

Answer 17

B-galactosidase

Question 18

Tay Sach’s disease (GM2 Gangliosidosis) is due to deficiency of what enzyme ?

Answer 18

hexosaminidase

Question 19

Niemann Pick disease is due to deficiency of what enzyme ?

Answer 19

sphingomyelinase

Question 20

Gaucher’s disease is due to deficiency of

Answer 20

glucosylceramidase

Question 21

in Mendelian disorders the primary fault is in what?

Answer 21

the structure of the gene

Question 22

what enzyme is deficient in Lesch Nyan syndrome ?

Answer 22

hypoxanthine-guanine phosphoribosyl transferase (HPRT)

Question 23

examples of autosomal dominant IEM

Answer 23

1) variegate porphyria
2) familial hypercholesterolaemia

Question 24

albinism is caused by deficiency of

Answer 24

tyrosinase in melanocytes

Question 25

Fabry’s disease is deficiency of

Answer 25

alpha-D-galactosidase enzyme