Which condition is defined by the combination of hypogonadotropic hypogonadism and anosmia?

Which condition is defined by the combination of hypogonadotropic hypogonadism and anosmia?

• A. Turner syndrome
• B. Androgen insensitivity syndrome
• C. Kallmann syndrome
• D. Klinefelter syndrome

Answer: (C)

This combination points to a developmental failure in GnRH neuron migration, leading to hypogonadotropic hypogonadism with anosmia. GnRH neurons originate outside the hypothalamus and migrate into it during development; if this migration is defective, the hypothalamus doesn’t release enough GnRH. That causes low LH and FSH, and consequently low sex steroids with delayed or absent puberty. The same defect also disrupts the olfactory system, producing anosmia. This classic pairing is Kallmann syndrome. Other conditions involve gonadal dysgenesis, androgen receptor issues, or chromosomal abnormalities but don’t typically include loss of smell, which helps distinguish this syndrome.

This combination points to a developmental failure in GnRH neuron migration, leading to hypogonadotropic hypogonadism with anosmia. GnRH neurons originate outside the hypothalamus and migrate into it during development; if this migration is defective, the hypothalamus doesn’t release enough GnRH. That causes low LH and FSH, and consequently low sex steroids with delayed or absent puberty. The same defect also disrupts the olfactory system, producing anosmia. This classic pairing is Kallmann syndrome. Other conditions involve gonadal dysgenesis, androgen receptor issues, or chromosomal abnormalities but don’t typically include loss of smell, which helps distinguish this syndrome.