Genetic disorders US Medical PG Flashcards - Medical Study Cards
Master Genetic disorders with OnCourse flashcards. These spaced repetition flashcards are designed for medical students preparing for NEET PG, USMLE Step 1, USMLE Step 2, MBBS exams, and other medical licensing examinations.
Genetic disorders Flashcard Deck - 7 Cards
Flashcard 11: Genetic basis and inheritance of Fragile X syndrome?
Answer: CGG repeat expansion in FMR1 gene; X-linked Dominant Inheritance.
Extra: Clinical features: macroorchidism (post-pubertal), long face, large prominent ears, intellectual disability, autism, mitral valve prolapse.
Genetics: CGG repeat expansion in the 5' untranslated region (UTR) of the FMR1 gene leads to hypermethylation and silencing of the gene.
Flashcard 12: What is the primary genetic defect and inheritance pattern in Achondroplasia?
Answer: Fibroblast growth factor receptor 3 (FGFR3) mutation (gain of function) leading to impaired chondrocyte proliferation.
Extra: Clinical features: Disproportionate short-limbed dwarfism (rhizomelia), macrocephaly with frontal bossing, midface hypoplasia, and normal trunk length. \nInheritance: Autosomal Dominant (AD), but ~80% are de novo mutations related to increased paternal age.
Flashcard 13: Cytogenetics and screening features of Down syndrome
Answer: 95% due to nondisjunction; may also be due to Robertsonian translocation or mosaicism.
Extra: Clinical Features: Intellectual disability, flat face, prominent epicanthal folds, simian crease, gap between first two toes.
Pregnancy Quad Screen (2nd Trimester):
- Increased: β-hCG, Inhibin A
- Decreased: AFP (α-fetoprotein), unconjugated estriol
Ultrasound (1st Trimester): Increased nuchal translucency.
Associations: Advanced maternal age, early-onset Alzheimer's disease, Trisomy 21.
Flashcard 14: Individuals with Down syndrome are predisposed to develop what conditions?
Answer: ALL and early onset Alzheimer's disease
Flashcard 15: What disease is most classically associated with meiotic nondisjunction?
Answer: Down syndrome (trisomy 21)
Flashcard 16: A child presents with a recessive disorder when only one parent is a carrier. What are three possible explanations?
Answer: infidelity, uniparental disomy, sporadic mutation
Flashcard 17: Clinical features and genetic defect in Osteogenesis Imperfecta?
Answer: Clinical features: Multiple unexplained fractures, blue sclerae, hearing loss, dental defects. Genetic defect: Type I collagen synthesis. Inheritance: Usually AD.
Extra: Osteogenesis imperfecta (OI) is often confused with child abuse due to multiple fractures. Clinical findings result from defective synthesis of type I collagen. \n\nKey features:\n- Multiple fractures (bone fragility)\n- Blue sclerae (translucency of connective tissue over choroidal veins)\n- Hearing loss (ossicle abnormalities)\n- Dental defects (dentinogenesis imperfecta)
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