Primary amenorrhoea with anosmia is seen in :
**Core Concept**
Kallmann syndrome is a rare genetic disorder characterized by delayed or absent puberty and anosmia (loss of smell), resulting from hypothalamic GnRH deficiency. This condition is caused by mutations in genes involved in the development of the olfactory and reproductive systems.
**Why the Correct Answer is Right**
In Kallmann syndrome, the GnRH neurons are either absent or hypoplastic, leading to a deficiency in GnRH secretion. This results in decreased gonadotropin secretion, causing hypogonadotropic hypogonadism and subsequent primary amenorrhea in females. Anosmia is due to the failure of olfactory bulb development, which is linked to the GnRH neurons. The genetic mutations affecting the KAL1 gene or other related genes are responsible for this condition.
**Why Each Wrong Option is Incorrect**
**Option A:** Turner syndrome is characterized by ovarian dysgenesis and primary amenorrhea, but it is not associated with anosmia. The genetic abnormality in Turner syndrome involves the X chromosome, leading to gonadal dysgenesis and estrogen deficiency.
**Option B:** Rokitansky syndrome (Mayer-Rokitansky-Küster-Hauser syndrome) is a condition of vaginal and uterine agenesis, resulting in primary amenorrhea. However, it is not associated with anosmia, and the primary issue is the absence of Müllerian duct development.
**Option C:** Congenital adrenal hyperplasia (CAH) can cause primary amenorrhea due to androgen excess and subsequent ovarian failure. However, it is not characteristically associated with anosmia.
**Clinical Pearl / High-Yield Fact**
Kallmann syndrome is a rare cause of primary amenorrhea, and a detailed history of anosmia should prompt further investigation for this condition. A key clinical clue is the presence of a family history, as many cases are inherited in an X-linked recessive pattern.
**Correct Answer: Kallmann syndrome**