This is a mechanism of disease flowchart for Klinefelter syndrome, covering the etiology, pathophysiology, pharmacology, and manifestations.
ADDITIONAL TAGS:
Azoospermia
+/- micropenis
Osteoporosis in adulthood
Risk factors / SDOH
Cell / tissue damage
Hormonal imbalance
Klinefelter syndrome
Medicine / iatrogenic
Infectious / microbial
Biochem / molecular bio
Other medical conditions
Signs / symptoms
Tests / imaging / labs
Embryology / development
Genetics / hereditary
Neurocog / psychiatry
Pathophysiology
+ Pharmacology
Etiology
Manifestations
Presence of a Barr body (inactivated X chromosome)
Karyotype: 47,XXY
(rarely 48,XXXY or 48,XXYY)
Nondisjunction of sex chromosomes during meiosis
Advanced maternal age
Testicular dysgenesis
Seminiferous tubules dysgenesis
Loss of Sertoli cells
↓ inhibin B
↑ FSH
Leydig cell dysgenesis
↑ LH
↓ testosterone
↑ conversion of testosterone to estrogen
↑ aromatase
↑ estrogen
Histo: (testicle biopsy post puberty):
- Seminiferous tubules fibrosis
- Leydig cells hyperplasia
Lifelong testosterone replacement
Eunuchoid habitus: delayed growth plate closure → tall, slim stature; long extremities
Gynecomastia
↓ facial and body hair
Testicular atrophy
↓ fertility and libido
Features of hypoandrogenism
Neurocog dysfunction (executive function, memory, intelligence), worse with more X
Language impairment
Poor social skills
Mitral valve prolapse
Metabolic syndrome
↑ risk of breast and testicular cancer
By Silver Spoon - Own work, CC BY-SA 3.0, [ Ссылка ]
