Genetic Disorders and Biochemical Pathology — Flashcards

Flashcard 101: Partial deficiency of _____ causes Kelley-Seegmiller syndrome.

Answer: HGPRTase

Flashcard 102: _____ is a tumor suppressor gene that encodes for the protein Tuberin

Answer: TSC2

Flashcard 103: _____ syndrome is an inherited defect in the alpha-3, 4, or 5 chains of type IV collagen.

Answer: Alport

Extra: Alport syndrome is most commonly X-linked (defect in the α5 chain). It affects the basement membranes of the kidney (glomerulonephritis/hematuria), inner ear (sensorineural deafness), and eye (e.g., anterior lenticonus). "Can't see, can't pee, can't hear high C."

Flashcard 104: The enzyme _____ is deficient in Lesch-Nyhan syndrome

Answer: HGPRT

Flashcard 105: Pyruvate dehydrogenase deficiency presents with _____ defects and lactic acidosis

Answer: neurologic

Flashcard 106: In OTC deficiency, the urea cycle is interrupted, leading to _____ and increased orotic acid levels.

Answer: hyperammonemia

Extra: OTC deficiency is the most common urea cycle disorder (X-linked recessive). Key features: 1. **Hyperammonemia**: Presents with lethargy, vomiting, and cerebral edema (due to glutamine accumulation in astrocytes). 2. **Increased Orotic Acid**: Excess carbamoyl phosphate is shunted into the pyrimidine synthesis pathway. 3. **Normal Glucose**: Unlike organic acidemias (e.g., propionic acidemia), urea cycle disorders typically present with **normal** blood glucose and respiratory alkalosis (due to ammonia-stimulated hyperventilation).

Flashcard 107: Propionic acidemia results in _____ levels of propionyl-CoA and decreased levels of methylmalonic acid

Answer: increased

Flashcard 108: Homocystinuria III due to _____ deficiency is treated with increased methionine in the diet

Answer: methionine synthase

Flashcard 109: Wilson disease results in lack of copper transport into _____ and lack of incorporation into ceruloplasmin

Answer: bile

Flashcard 110: _____ syndrome is due to absent UDP-glucuronyl transferase activity

Answer: Crigler-Najjar