Inborn Errors of Metabolism

Question 1

Define PKU

Answer 1

Phenylketouria: a buildup of phenylketoacids in the blood and urine

Question 2

CMs of PKU

Answer 2

seizure, pale complexion, eczema

Question 3

SP for PKU

Answer 3

plasma phenylalanine test at birth

Question 4

Define Galactosemia

Answer 4

G1PUTase deficiency –> increased blood galactose levels

Question 5

CMs for Galactosemia

Answer 5

vomiting, jaundice, and hepatomegaly on initiation of lactose-containing feedings

Question 6

SP for Galactosemia

Answer 6

PT prolongation, together with proteinuria and aminoaciduria

Question 7

Define SCD

Answer 7

Sickle cell disease: Altered hgb shapes –> altered RBC shapes/behavior

Question 8

CMs for SCD

Answer 8

anemia, jaundice, MS pain

Question 9

SP for SCD

Answer 9

at-risk neonates: hgb test (molecular screen)

Question 10

Define Maple Syrup Urine Disease

Answer 10

branched-chain alphaketoaciduria: deficient or inhibited breakdown of alphaketoacids like leucine, isoleucine & valine

Question 11

CMs for Maple Syrup Urine Disease

Answer 11

MSU, encephalopathy

Question 12

SP for Maple Syrup Urine Disease

Answer 12

plasma: increased branched chain amino acids

Question 13

Define homocystinuria

Answer 13

decreased cystathionine-beta-synthase (CBS)/MTHFR/B12 –> increased homocystine, methionine

Question 14

CMs for homocystinuria

Answer 14

marfanoid, dislocated lenses, thrombus

Question 15

SP for homocystinuria

Answer 15

high blood levels of homocystine and/or methionine

Question 16

Define biotinidase deficiency

Answer 16

genetic deficiency –> decreased biotin –> decreased carboxylases –> lactic acidosis and hyperammonemia

Question 17

CMs for biotinidase deficiency

Answer 17

hypotonia, skin problems

Question 18

SP for biotinidase deficiency

Answer 18

LA+osis –> biotinidase serum assay

Question 19

Define Congenital Adrenal Hyperplasia

Answer 19

increased 17-Hydroxyprogesterone –> decreased cortisol –> increased ACTH –> hyperplasia of kidneys/adrenal glands

Question 20

CMs for Congenital Adrenal Hyperplasia

Answer 20

increased linear growth/skeletal maturation, genital virilization, labial fusion, urogenital sinus

Question 21

SP for Congenital Adrenal Hyperplasia

Answer 21

hyponatremia, hyperkalemia, MA+osis –> hormone studies

Question 22

Define Hearing Loss

Answer 22

Non-/genetic (50/50), non-/syndromic causes of hearing loss; biggest genetic cause: GJB2

Question 23

CMs for Hearing Loss

Answer 23

Not a trick question: inability to hear

Question 24

SP for Hearing Loss

Answer 24

High-risk: screen @ every well-visit from birth to 3 years

Question 25

Define Congenital Hypothyroidism

Answer 25

Genetic malformation/-adaptation of THPT pathway leading to decreased production of T3/4

Question 26

CMs for Congenital Hypothyroidism

Answer 26

thick tongue, jaundice, umbilical hernia

Question 27

SP for Congenital Hypothyroidism

Answer 27

neonatal blood TSH (high) and T4 (low) levels

Question 28

Define MCAD Deficiency

Answer 28

Medium-chain acyl-CoA dehydrogenase (MCAD) deficiency is the most common fatty acid oxidation disorder

Question 29

CMs for MCAD Deficiency

Answer 29

Reye-like episodes: confusion, cephaledema, liver damage

Question 30

SP for MCAD Deficiency

Answer 30

fasting ketogenesis (decreased) screen, acylcarnitine profile (increased octanoylcarnitine)