Source / episode info

• **Episode:**423
• **Title:**Divine Intervention Episode 423: USMLE Step 2/3 Rapid Review Series 86
• **Published:**2022-11-01
• Source:Episode page

One-liner

This episode provides a rapid review covering high-yield genetic disorders defined by repeat expansion (Fragile X, Huntington's), age-specific hip pathologies (DDH, LCPD, SCFE), the clinical presentation of conversion disorder, and critical pediatric abdominal masses like Wilms Tumor, along with associated syndromes.

High-yield summary

• Genetic Disorders: Know the specific gene, repeat expansion type, and chromosome location for Fragile X (FMR1, CGG on X); Huntington's (HTT, CAG on Chr 4); Myotonic Dystrophy (DMPK, CTG on Chr 19).
• Hip Pathology Progression: The typical age progression of hip issues is Developmental Dysplasia of the Hip (newborn) -> Legg-Calvé-Perthes Disease (young males <10 years) -> Slipped Capital Femoral Epiphysis (obese adolescents >10 years).
• Wilms Tumor: Classically presents as a flank mass that does not contain calcifications. True hematuria is confirmed by seeing actual red blood cells on microscopy, distinguishing it from myoglobinuria.
• WAGR Complex: A constellation of findings: Wilms Tumor + Aniridia + Genitourinary anomalies + Intellectual Disability.
• Conversion Disorder: Defined by neuro deficits that are bizarre and lack a rational neurological localization; the patient often exhibits a "don't care" attitude toward symptoms.

Learning objectives

• Identify the genetic basis, repeat expansion type, and chromosomal location for major X-linked dominant disorders (Fragile X).
• Differentiate between age-specific hip pathologies: DDH, LCPD, and SCFE.
• Recognize the classic presentation of Wilms Tumor and its associated syndromes (WAGR, BWS, DDS).
• Apply clinical reasoning to diagnose conversion disorder based on inconsistent neurological findings and patient demeanor.
• Understand the pathophysiology of avascular necrosis in pediatric hip joints.

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