Metabolic Disorders of Urea Cycle, Complex Molecules, and Carbohydrates MCQs

Infants with bilateral choanal atresia who have difficulty with mouth breathing make vigorous attempts to inspire, often suck in their lips, and develop cyanosis. Distressed children then cry (which relieves the cyanosis) and become calmer, with normal skin color, only to repeat the cycle after closing their mouths. This is called cyclic cyanosis. Also note that bilateral choanal atresia is often a part of CHARGE Syndrome. Reference: OP Ghai Essential Pediatrics, 10 th Edition, Page Number-388.

The diagnosis is Tuberous sclerosis, with the child having Infantile Spasms. In such a case, Vigabatrin is more efficacious than ACTH. Vigabatrin (VGB) is a structural analogue of the inhibitory neurotransmitter gamma-aminobutyric acid (GABA) and irreversibly inhibits the GABA degradative enzyme GABA-transaminase (GABA-T), thus increasing brain levels of GABA. VGB is very effective against infantile spasms associated with tuberous sclerosis complex (TSC), and it is the first-choice drug of in this case based on many reports. Reference: Nelson textbook of pediatrics, 1 st SE edition, pg. 2879

ERT has emerged as one of the most important advances in the treatment of sphingolipidoses. ERT with biweekly infusions of recombinant human glucocerebrosidase is invariably effective in reversing the hematologic and early skeletal complications of Gaucher disease. None of the other options listed above are valid treatment options for Gaucher disease. Reference: Nelson textbook of Pediatrics, 1 st SA ed., pg. 708

Patients may have bruising from thrombocytopenia, chronic fatigue secondary to anemia, hepatomegaly with or without elevated liver function test results, splenomegaly, and bone pain. Most patients develop radiologic evidence of skeletal involvement, including an Erlenmeyer flask deformity of the distal femur. Reference: Nelson textbook of pediatrics, 1 st SA ed., pg. 709

Galactosemia is a disorder of carbohydrate metabolism in which early ingestion of galactose, found in breast milk and cow's milk formula, leads to jaundice, lethargy, vomiting, acidosis, cataracts, failure to thrive, and bleeding; Lab abnormalities may include indirect hyperbilirubinemia and coagulopathy, and urinalysis with reducing substances present but negative glucose on dipstick. Infants with galactosemia commonly present with gram-negative rod UTI or urosepsis, especially with E coli, such as in this patient. Reference: Nelson textbook of Pediatrics, 1 st SA ed., pg. 726

Hunter syndrome is inherited as an X-linked condition. All the other MPSs are autosomal recessive (like most IEM). Males with Hunter syndrome present fairly similar to patients with Hurler syndrome. Hunter syndrome is not associated with corneal clouding, which is part of Hurler. It is important to check for carrier status in mothers of affected males with Hunter syndrome to establish appropriate recurrence risks. Reference: Nelson textbook of Pediatrics, 1 st SA ed., pg. 739

Patients with the infantile form of Tay-Sachs disease have clinical manifestations in infancy including loss of motor skills, increased startle reaction, and macular pallor and retinal cherry-red spots. Affected infants usually develop normally until 4-5 months of age when decreased eye contact and an exaggerated startle response to noise (hyperacusis) are noted. Macrocephaly, not associated with hydrocephalus, may develop. In the 2nd year of life, seizures develop which may be refractory to anticonvulsant therapy. Neurodegeneration is relentless, with death occurring by the age of 4 or 5 years. The juvenile and later-onset forms initially present with ataxia and dysarthria and may not be associated with a macular cherry-red spot. Reference: Nelson Textbook of Pediatrics, 20 th ed., pg. 708