Source / episode info
- **Episode:**357
- **Title:**Divine Intervention Episode 357 – The Clutch Disorders of Sexual Differentiation Review (for Step 1-3)
- **Published:**2021-12-16
- Source:Episode page
One-liner
This episode provides a deep dive into the pathophysiology of DSDs, covering sex determination mechanisms (AMH/testosterone), specific syndromes (AIS, MRKH, CAH), and related endocrine topics like aromatase deficiency and Turner syndrome.
High-yield summary
- Male Development: The Y chromosome's SRY gene initiates testicular development. Sertoli cells produce Anti-Müllerian Hormone (AMH) to regress the Müllerian duct derivatives (uterus, fallopian tubes). Leydig cells produce testosterone, which is converted by 5-alpha reductase into Dihydrotestosterone (DHT) for external virilization and Wolffian duct maintenance.
- MRKH Syndrome: A 46,XX karyotype with normal ovaries/gonads but failure of Müllerian development (uterus, upper vagina). The lower third of the vagina is typically spared because it develops from the urogenital sinus.
- Androgen Insensitivity Syndrome (AIS): Genetically male (46,XY) but phenotypically female due to defective androgen receptors. Internal structures are absent (due to normal AMH action), and external genitalia remain female because DHT cannot bind its receptor.
- Congenital Adrenal Hyperplasia (CAH): Most commonly 21-hydroxylase deficiency. Deficiency leads to massive accumulation of adrenal androgens, causing virilization in females (ambiguous genitalia). Labs: Hyponatremia, hyperkalemia, metabolic acidosis (Type 4 RTA).
- Turner Syndrome (45,X): Characterized by streak ovaries and primary amenorrhea. Due to ovarian failure, there is no negative feedback on the pituitary, resulting in high FSH/LH levels (Hypergonadotropic Hypogonadism).
Learning objectives
- Differentiate the hormonal roles of AMH, testosterone, and estrogen in male and female reproductive tract development.
- Recognize the classic biochemical triad associated with 21-hydroxylase deficiency (CAH).
- Distinguish between genetic sex karyotypes (46,XY vs 46,XX) and resulting phenotypes (e.g., AIS vs MRKH).
- Understand the hormonal feedback loops governing gonadal function in primary ovarian failure (Turner Syndrome).
- Identify the clinical implications of enzyme deficiencies like aromatase deficiency or 5-alpha reductase deficiency.
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