Kallmann syndrome: a genetic condition characterized by an absent sense of smell along with absent or delayed puberty. It is a type of hypogonadotrophic hypogonadism, a situation in which the production of hormones that control sexual development is impaired. Most affected persons do not develop secondary sexual characteristics at puberty. Males may have a small penis (micropenis) and undescended testes, while females have little breast development and typically do not begin to menstruate. The clinical features of the disease can vary among individuals, and other birth defects can be associated with the syndrome. Four types of Kallmann syndrome have been identified, depending on the exact genes that are affected. Kallmann syndrome is more common in males than in females and occurs in 1 in 10,000 to 86,000 people. The most common form of the condition is inherited in an X-linked recessive pattern of inheritance, although other forms may be inherited in autosomal dominant or recessive patterns.
REFERENCE: Genetics Home Reference. Kallmann syndrome.