Kallmann syndrome

Kallmann syndrome, also known as olfactogenital syndrome, is a very rare, genetically determined congenital disorder that occurs more frequently in males than in females and primarily affects sexual maturation.

The cause of this disorder is a mutation in several genes, which leads to abnormalities in the development of the olfactory system as well as dysfunction of the hypothalamus, a part of the brain responsible for proper sexual development of the individual, which is therefore impaired. The cause of the symptoms lies in reduced levels of hormones that regulate the secretion of sex hormones and the development of the testes and ovaries, resulting in reduced function of these glands.

This syndrome occurs with a frequency of approximately 1:8,000 in boys and 1:40,000 in girls. Kallmann syndrome was described based on typical clinical features as early as the first half of the last century.

Diagnosis

Diagnosis is still not fully established at present. Kallmann syndrome arises from mutations in various genes; in approximately 50% of patients, no gene mutation can be identified. Kallmann syndrome may also be inherited through different patterns of inheritance.

Treatment

Administration of sex hormones is used to alleviate symptoms and support proper development of the reproductive organs, thereby promoting the development of secondary sexual characteristics; however, the impairment of the sense of smell remains incurable.

• anosmia – impaired sense of smell
• hypogonadism – underdevelopment and dysfunction of the gonads (reduced function)
• gonadotropin deficiency – hormones regulating the gonads
• in affected individuals, typical puberty does not occur
• absence of typical secondary sexual characteristics; boys do not undergo voice deepening
• cryptorchidism – impaired testicular descent in boys
• micropenis in young boys
• abnormalities of pubic hair (sparse or absent)
• in girls, absence of menstruation
• lack of breast development
• frequently also hearing impairment, cleft defects (e.g. facial clefts), color blindness or visual impairment, and disturbed dental development
• impaired kidney development
• in some individuals, signs of intellectual disability
• osteoporosis (due to deficiency of sex hormones)