The clue given in many cases is the lack of smell (anosmia) in a boy with delayed puberty.
About Kallmann's Syndrome
- Kallmann's Syndrome is an inherited form of secondary hypogonadism.
- It involves a congenital lack of development of the olfactory lobes.
- Deficiency in gonadotropin-releasing hormone (GnRH) secretion.
Genetics
- It can be inherited in an X-linked recessive (XLR), autosomal dominant (AD), or autosomal recessive (AR) pattern.
Aetiology
- Abnormalities in the KAL-1 or KAL-2 genes, which encode anosmin-1 and FGF-1, respectively, are implicated.
- Approximately 50% of cases are thought to have a genetic inheritance, while the rest are sporadic.
- Kallmann's Syndrome results from the failure of GnRH-secreting neurons to migrate to the hypothalamus during development.
Clinical Features
- Anosmia (deficient sense of smell).
- Secondary hypogonadism (hypogonadotropic hypogonadism).
- Associated features include cleft palate and colour blindness.
- Delayed puberty, hypogonadism, and cryptorchidism (undescended testes).
Investigations
- Reduced serum testosterone levels.
- Low or normal luteinizing hormone (LH)
- Low follicle-stimulating hormone (FSH) levels (high levels seen in Klinefelter's syndrome).
- MRI shows absent olfactory bulbs.
- Fluorescence in situ hybridization (FISH), using a specific chromosomal probe, is currently the best method for a genetic diagnosis of this condition.
Management
- Supportive care, including hormone replacement therapy if needed.
- Genetic counseling is recommended for affected families.