IEM general + carbohydrate disorders

Question 1

inborn errors of metabolism disorders

Answer 1

group of disorders where a single gene defects causes clinically significant block in a metabolic pathway

Question 2

metabolic processes consist of…

Answer 2

enzymes and substrates

Question 3

enzymes

Answer 3

proteins encoded by genes

mediate catalytic steps in metabolism

Question 4

mutations of`enzymes

Answer 4

reduce the efficiency of encoded enzymes to a level at which normal metabolism can occur

Question 5

how are inborn errors of metabolism characterized?

Answer 5

1. accumulation of substrate
2. deficiency of product

Question 6

how are inborn errors of metabolism typically transmitted?

Answer 6

autosomal recessive or x-linked

Question 7

when do most IEMs presnet

Answer 7

infancy

frequencies of ea. individual IEM is rare, but collectively they show often

prevention of death or permenant damages is dependent on early diagnosis and starting appropriate therapy

Question 8

categories of inborn error of metabolism

Answer 8

• carbohydrate disorders
• amino acid disorders
• urea cycle disorders
• lipid disorders
• heavy metal transport defects

Question 9

carbohydrate disorders discussed in this class

Answer 9

galactosemia

hereditary fructose intolerance

Question 10

galactosemia (forms)

Answer 10

3 forms of the dz

only need to know classic galactosemia - most common and more severe

autosomal recessive

Question 11

galactosemia

genetic abnormality

Answer 11

mutation of gene encoding GALT

single missense mutation in exon 6

Question 12

galactosemia

enzyme effected

Answer 12

GALT

Question 13

galactosemia

pathophysiology

Answer 13

gene mutation causing diminshed activity of GALT

loss of function mutation

diminished GALT means they cannot effectivly break down galactose

galactose accumulates in the lens leading to increased osmotic pressure and protein denaturation and cataract formation

Question 14

galactosemia

effect on substrate

Answer 14

build up of galactose and byproduct of partial galactose breakdown

Question 15

galactosemia

clinical manifestations

Answer 15

infends develop in weeks after they are given milk

• failure to thrive
• heptaomegaly and cataracs

Question 16

galactosemia

results of early detection

Answer 16

IQ is still low despite early and adequate therapy

Question 17

galactosemia

treatment

Answer 17

measures plasma GALT activity from dried drip of blood

treatment involves complete removal of milk (lactose) from the diet

if untreated= severe mental retardation and is often fatal

Question 18

hereditary glucose intolerance

inheritance

Answer 18

autosomal revessive

deficiency of fructose-1-phosphate aldolase

Question 19

hereditary glucose intolerance

enzyme

Answer 19

fructose-1-phosphate aldolase deficency

Question 20

hereditary glucose intolerance

effect on substrate/byproduct

Answer 20

unable to breakdown fructose

found in artificial sweetener and fruits

Question 21

hereditary glucose intolerance

pathophys

Answer 21

accumulation of fructose-1-p in the liver, kidney, and small intestine

accumlation inhibits glycogen breakdown and glucose synthesis causing severe hypoglycemia following fuctose ingestion

free fructose in blood results in acceleration in production of uric acid which competes with lactate for renal tubule excretion = lactic academia

Question 22

hereditary glucose intolerance

clinical manifestaions

Answer 22

classic symptom is severe hypoglycemia following fuctose ingestion

metabolic alkadosis

Question 23

hereditary glucose intolerance

treatment

Answer 23

elimination of furctose in diet (fruits, table sugar, etc)

prognosis is excellent for infants who recieve rapid diagnosis and treatment

normal life expectancy