METABOLIC DISORDERS

Question 1

Newborn with a high ammonia level, normal anion gap, and respiratory alkalosis. What metabolic disorder category is this likely to be ?

Answer 1

Urea cycle defect (UCD)

Question 2

Newborn with poor feeding, vomiting, elevated ammonia levels, and respiratory alkalosis and elevated citrulline levels

Answer 2

Citrullinemia-UCD

Question 3

Child presents with ammonia level 2000 μmol/L, low BUN, with respiratory alkalosis without ketoacidosis and high levels of orotic acid

Answer 3

Ornithine transcarbamylase deficiency
(OTC)-UCD

Question 4

What are the initial steps of urea cycle defect (UCD) management?

Answer 4

Reduce protein intake, correct respiratory alkalosis

Question 5

Normal to high ammonia level with a high-anion gap acidosis. What metabolic category is this likely
to be?

Answer 5

Organic acidemia

Question 6

A neonate with severe ketoacidemia with or without elevated ammonia level, and long-term complication is associated with cardiomyopathy

Answer 6

Propionic acidemia

Question 7

Which metabolic disease can cause
encephalopathy and is associated with an odor of sweaty feet?

Answer 7

Isovaleric acidemia

Question 8

Which metabolic disease presents with retinal hemorrhage and intracranial bleeding and can be mistaken for child abuse?

Answer 8

Glutaric aciduria type I

Question 9

A 1-week-old presents with severe metabolic acidosis, poor feeding, opisthotonos, absent Moro reflex, seizures, and urine with a “caramel-like
odor”

Answer 9

Maple urine syrup disease
Treatment: restrict leucine intake

Question 10

What is the category of these amino acids: valine, leucine, and isoleucine?

Answer 10

Three branched-chain amino acids

Question 11

A 6-month-old has alopecia, encephalopathy; skin rash looks like acrodermatitis enteropathica

Answer 11

Biotinidase deficiency or holocarboxylase synthetase deficiency

Question 12

A 2-year-old girl presents with seizures, tachypnea, and drowsiness; she has been having diarrhea, vomiting, and loss of appetite for the last few days.
Her labs showed hypoglycemia, low ketones, and hyperammonemia

Answer 12

Medium-chain acyl-CoA dehydrogenase
(MCAD) deficiency (due to fatty acid oxidation defect, she is unable to increase ketone body production after glucose consumption during fasting or metabolic stress due to illness)

Question 13

Child presents with a musty odor, eczema, fair skin and hair, and intellectual disability

Answer 13

Phenylketonuria (PKU)

Question 14

Newborn with positive PKU on newborn
screening. What is the next best step?

Answer 14

Start low-protein diet and a phenylalanine-free medical formula as soon as possible. Then confirm with genetic testing

Question 15

What is the major consequence of delaying dietary restriction in children with PKU?

Answer 15

Irreversible intellectual disability in most
children

Question 16

Black pigments in the diapers, unusually dark urine few days after birth; when older, develops blue discolorations in the ear cartilage and palpable calcifications in the discolored areas, arthritic symptoms in the spine, hip and knee

Answer 16

Alkaptonuria

Question 17

Child with an intellectual disability, normal aorta, pectus excavatum, increased risk of clotting, along with downward dislocation of the lens (ectopia lentis)

Answer 17

Homocystinuria (in Marfan syndrome the lens is dislocated upward and no intellectual disability)

Question 18

Infant with failure to thrive, hepatomegaly; renal tubular acidosis may be associated with hepatoblastoma

Answer 18

Tyrosinemia type I (hepatorenal)

Question 19

Type of tyrosinemia associated with intellectual disability, corneal ulcers, and painful skin lesions on the palms and soles

Answer 19

Tyrosinemia type II (oculocutaneous
tyrosinemia)

Question 20

A 4-week-old infant presents with vomiting, seizure, jaundice, poor weight gain, hepatosplenomegaly, cataracts, and reduced substance in the urine

Answer 20

Galactosemia (galactose 1-phosphate
uridyltransferase deficiency)

Question 21

Infant had sepsis before the diagnosis of galactosemia. What was the most likely cause?

Answer 21

Escherichia coli (E. coli)

Question 22

Healthy infant presents with cataracts only. What is the most likely cause?

Answer 22

Galactokinase deficiency

Question 23

A 4-month-old, doll-like face with prominent cheeks, short stature, thin extremities, protuberant abdomen, hepatomegaly, hypoglycemia, seizures,
lactic acidosis, hyperuricemia, and hyperlipidemia

Answer 23

Type I glycogen storage disease (von Gierke disease)

Question 24

What is the best management of infants with von Gierke disease?

Answer 24

Continuous feeding at night with nasogastric tube

Question 25

Cramps with exercise, burgundy colored urine after exercise, elevated creatine phosphokinase (CPK), and ammonia levels after exercise

Answer 25

McArdle disease (type V glycogen storage disease)

Question 26

A 6-week-old infant previously normal presents with muscle weakness, hypotonia, large tongue, hepatomegaly, hypertrophic cardiomyopathy, congestive heart failure, elevated CPK,
transaminases, and LDH; muscle biopsy shows vacuoles full of glycogen

Answer 26

Pompe disease (type II glycogen storage
disease)

Question 27

A previously healthy 7-month-old infant with new-onset seizures, vomiting, and lethargy that started after fruit juice was introduced

Answer 27

Fructokinase 1,6, diphosphatase deficiency

Question 28

An 18-month-old with inguinal and umbilical hernias, now presents with progressive developmental delay, coarse facial features, macroglossia, macrocephaly > 95%, hepatosplenomegaly, corneal clouding, retinal disease, and deafness

Answer 28

Hurler syndrome
Mucopolysaccharide (MPS) type I

Question 29

An 18-month-old boy, previously healthy, presents with progressive developmental delay, coarse facial
features, macroglossia, macrocephaly > 95%, hepatosplenomegaly, no corneal clouding

Answer 29

Hunter syndrome
MPS type II (X-linked recessive)

Question 30

Child previously normal presents with a
progressive intellectual decline, temper tantrums, hyperactivity, destructive and aggressive behavior, pica and sleep disturbances, now becomes immobile and unresponsive

Answer 30

Sanfilippo syndrome
MPS type III

Question 31

Acroparesthesia or episodes of extremities with burning pain, anhidrosis, fever, proteinuria,
hypertension, angiokeratomas (painless papules on the skin), and clouding of the cornea

Answer 31

Fabry disease (X-linked recessive)

Question 32

A 3-year-old of Ashkenazi Jewish presents with severe splenomegaly, lytic bone lesions, and decreased glucocerebrosidase levels

Answer 32

Gaucher disease type I

Question 33

A 2-month-old infant startles easily to any noise, does not diminish with repeated stimuli, hypotonia, progressive muscle weakness, extremity hypertonia, large head, noises trigger seizures, macular cherry-red spot, and no organomegaly

Answer 33

Tay–Sachs disease

Question 34

A 4-year-old child, dysphagia, abnormal eye movement, ataxia, hepatosplenomegaly, cataplexy when scared, and narcolepsy

Answer 34

Niemann–Pick disease

Question 35

Infant with a history of developmental delay, Myopathy, Encephalopathy, Lactic Acidosis, and Stroke

Answer 35

(MELAS) syndrome

Question 36

Ptosis, ophthalmoplegia, ragged-red fiber myopathy

Answer 36

Mitochondrial DNA (mtDNA) mutation

Question 37

An 18-year-old develops ophthalmoplegia, night blindness, ataxia, heart block, muscle weakness,
proximal myopathy, short stature, and
hypogonadism

Answer 37

Kearns–Sayre syndrome

Question 38

A 12-year-old, ataxia, hypoactive or absent deep tendon reflexes, impaired vibratory and proprioceptive functions, hypertrophic cardiomyopathy, and diabetes mellitus

Answer 38

Friedreich ataxia

Question 39

Boy, biting his lips, and fingers; normal at birth, had difficulty gaining weight in the 1st year of life, uric acid level is elevated

Answer 39

Lesch–Nyhan disease

Question 40

What is the enzyme deficiency in patients with Lesch–Nyhan disease?

Answer 40

Hypoxanthine-guanine
phosphoribosyltransferase (HGPRT

Question 41

How is Lesch–Nyhan disease transmitted?

Answer 41

X-linked recessive

Question 42

Loss of developmental milestones; failure to thrive; truncal hypotonia; abnormal kinky hair, eyebrows,
and eyelashes

Answer 42

Menkes disease or kinky hair disease

Question 43

How is Menkes disease transmitted?

Answer 43

X-linked; causes an impaired copper intake

Question 44

Child with cholesterol 650 mg/dL, tendon xanthoma, father died at age 23 with a heart attack

Answer 44

Familial hypercholesterolemia