Inborn Errors of Metabolism/Aminoacidurias

Question 1

Cystinuria (and cystinosis) is _____ and is tested with _____.

Answer 1

An increase in cysteine. Cyanide nitroprusside.

Question 2

Cystinosis

Answer 2

Intracellular deposition of cysteine within lysosomes.

Sx include Polyuria, Polydipsia, Dehydration, Vomiting

Question 3

_____ readily pass through glomerular filtration barrier and are reabsorbed in the proximal tubule.

Answer 3

Amino acids

Question 4

Maple Syrup Urine Disease

Answer 4

BCKA (keto-acids) – eg, Leucine, Isoleucine, Valine increase in blood, CSF, urine

Prenatal and neonatal screening commonly detect MSUD

Question 5

Cystic Fibrosis

Answer 5

AR disease affecting lungs, pancreas, liver, kidney, intestine. Sweat tests (collection and measurement of sweat), newborn screening, genetic tests are used to test for CF

An AR genetic disease that causes difficulty breathing and lung infections due to mucus buildup

Question 6

Cystic fibrosis affects _____.

Answer 6

mostly the lungs but also pancreas, liver, kidneys, intestines

Question 7

CF requires _____ faulty genes. Chloride ions in CF _____.

Answer 7

2 faulty genes

Cl- ions are blocked from leaving lung cells due to missing or mutated CFTR

Question 8

CFTR

Answer 8

Cystic fibrosis transmembrane (conductance) regulator

Question 9

Hartnup Syndrome

Answer 9

Pellegra-like dermatosis. Affects absorption of nonpolar amino acids – eg, tryptophan

Question 10

PKU

Answer 10

Phenylalanine buildup in blood from a lack of phenylalanine hydroxylase.

Question 11

Tyrosinosis/Tyrosinemia

Answer 11

Defect in fumarylacetoacetase (tyrosine levels increase in blood and urine)

Question 12

Laboratory test for tyrosinosis

Answer 12

Ion-exchange column chromatography

Question 13

Results of tyrosinosis

Answer 13

Liver failure, rickets, renal tubular dysfunction and polyneuropathy

Question 14

First discovered inborn error of metabolism

Answer 14

Alkaptonuria

Question 15

In alkaptonuria, urine, plasma, cartilage, and connective tissue can turn

Answer 15

Black

Question 16

Homocysteinuria is an excess of
Homocysteinuria is a deficiency of
Why is homocysteinuria difficult to measure?

Answer 16

homocysteine in urine
cystathionine beta synthase
Difficult to measure (bound to other thiols)

Question 17

MSUD

Answer 17

Maple Syrup Urine Disease: Rare genetic disorder involving deficiency of branched chain alpha keto acid dehydrogenase complex

Question 18

MSUD is a buildup of

Answer 18

Leucine, Isoleucine, Valine

Question 19

MSUD uses a modified _____.

Answer 19

Guthrie test that detects elevated plasma Leucine

Question 20

Alkaptonuria is an accumulation of _____ due to _____.

Answer 20

Homogentisic acid (HGA) accumulation due to homogentisate oxidase

Question 21

Problems resulting from alkaptonuria (3)

Answer 21

Heart problems, kidney stones, prostate stones

Question 22

Ochronosis

Answer 22

Buildup of black pigmentation in connective tissue.

Question 23

Tryptophan can be converted into _____, _____, and _____.

Answer 23

5 HT, melatonin, niacin

Question 24

Proximal tubular cells are unable to reabsorb amino-acids in this condition

Answer 24

Cystinosis

Question 25

Most common cause of Fanconi syndrome (inadequate reabsorption by proximal renal tubule).

Answer 25

Cystinosis

Question 26

Most metabolic disorders are _____ (genetically).

Answer 26

Autosomal recessive