Genetic Disorders and Biochemical Pathology — Flashcards

Flashcard 111: _____ 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 112: 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 113: Which step of thyroid hormone synthesis is impaired in pendred syndrome?_____

Answer: organification

Flashcard 114: Alagille syndrome is associated with mutations in _____ gene in 90% of patients

Answer: JAG1

Flashcard 115: Mutation of the genes encoding _____ causes juvenile hemochromatosis

Answer: hemojuvelin (HJV)

Flashcard 116: Sphingomyelinase gene is present on chromosome _____

Answer: 11

Flashcard 117: What is the mode of inheritence of Behr's syndrome?_____

Answer: Autosomal recessive

Flashcard 118: Which gene mutation is implicated in Imerslund-Grasbeck syndrome?_____

Answer: AMN

Flashcard 119: What is the mode of inheritence of congenital erythropoetic porphyria?_____

Answer: Autosomal recessive

Flashcard 120: Occipital horn syndrome (Ehlers Danlos-IX; cutis laxa) occurs due to _____ gene mutation

Answer: ATP7A