Condition: Kallmann Syndrome

Kallmann syndrome is a rare inherited disorder that mostly, but not exclusively, affects men. The major characteristics of Kallmann syndrome, in both men and women, are the failure to experience puberty and the complete or partial loss of the sense of smell.

Failure to go through puberty reflects a hormonal imbalance that is caused by a failure of a part of the brain known as the hypothalamus. Patients with Kallmann syndrome show evidence of small genitalia, sterile gonads that cannot produce the sex cells (hypogonadism), and a loss of the sense of smell (anosmia). The impaired production of hormones as well as sperm and egg cells causes delayed puberty, growth and infertility.

There are three forms of Kallmann syndrome. The most common is known as KAL1. This is an X-linked form, which means that the malfunctioning gene is located on the X chromosome. The malfunctioning gene responsible for the next more common form, KAL2, has been traced to a site on chromosome 8 and the genetic inheritance is transmitted as an autosomal dominant trait. The third and most rare form of Kallmann syndrome is KAL3. This appears to be transmitted as an autosomal recessive trait. The site of the malfunctioning gene has not been determined.