Curriculum · Metabolic and Endocrine and Diabetes Mellitus
Kallmann syndrome
What it is
Kallmann syndrome is a rare genetic disorder of delayed or absent puberty, first described by Kallmann and Schoenfeld in 1944. It is caused by an inability to produce the hormones for sexual maturation. It affects males 4 times more frequently than females. Among the causes of pubertal delay it belongs to the pathologic group, under hypogonadotropic hypogonadism.
Causes and risk
The defect is in neurons. In the GnRH-releasing neurons, less GnRH means less LH and less FSH, and with that a low gonadal function: low testosterone in males and low progesterone in females. In the olfactory neurons, which share the olfactory placode with them, the result is hyposmia, a reduced sense of smell, or anosmia, complete loss of smell. A positive family history is part of the described syndrome.
How it presents
Puberty is delayed or absent, and secondary sexual characteristics are delayed in both males and females. The symptoms are impaired smell, a small penis and undescended testis. The loss of smell may be only partial, so a man may reach an infertility clinic with no complaint apart from partial loss of smell. Cleft lip, cleft palate, hearing loss, tooth loss and kidney issues are common.