Kallmann Syndrome

Congenital syndrome characterized by the association of hypogonadotropic hypogonadism with anosmia (or hyposmia).

de Morsier Syndrome II; Hypogonadotropic Hypogonadism and Anosmia Syndrome; Kallmann-de Morsier Syndrome; Maestre-Kallmann-de Morsier Syndrome; Maestre de San Juan-Kallmann Syndrome; Maestre de San Juan-Kallmann-de Morsier Syndrome; Olfactogenital Dysplasia; Morsier-Gauthier Syndrome.

Genetic disorder first described in 1856 by the Spanish histologist Aureliano Maestre de San Juan (1828-1890). The German psychiatrist Franz Josef Kallmann in 1944 pointed out the genetic background of the disease, while the Swiss pathologist Georges de Morsier published a case series in 1954.

1:10,000 males, 1:50,000 females of live births.

X-linked recessive, also present in autosomal recessive and autosomal dominant forms; locus on X chromosome at position 22.3 (Xp 22.3). In the X-linked form, there is a mutation in gene KALIG-1, which encodes for a protein with homology to neural cell-adhesive molecule (N-CAM); this form can be linked to X-linked ichthyosis, mental retardation, chondrodysplasia punctata, and short stature. Male-to-female ratio is 5:1

Interference with the migration of endogenous gonadotropin-releasing hormone (GnRH)-secreting cells arising from the nasal placode (precursor of the nose) to the hypothalamus during fetal life resulting in agenesis of the olfactory lobes and GnRH deficiency.

Clinical features, biochemical (low serum levels of androgens and positive response to GnRH stimulation), and MRI/CT imaging (unilateral or bilateral absent olfactory bulbs).

Highly variable, but characterized by GnRH deficiency with hypogonadotropic hypogonadism, delayed incomplete or absent puberty, short stature, and smelling deficiencies. Neurosensory hearing loss and mild mental retardation have been reported, but the majority of these patients have normal intelligence. Choanal atresia and cleft palate and/or lip are other common features. Renal anomalies include unilateral renal agenesis and cryptorchidism in males. Infertility, erectile dysfunction, and decreased libido are common in untreated patients. Most patients have normal lifespan. Kallmann syndrome is occasionally associated with congenital heart diseases (atrial and ventricular septal defects, transposition of the great arteries, Ebstein anomaly, aortic arch anomalies, but also atrioventricular block, bundle branch blocks, and even Wolff-Parkinson-White syndrome).

Assess cardiac function and rule out any anomalies and obtain further examinations (ECG, echocardiography) if required. Evaluate renal function (creatinine, urea). Examine for any indicators of difficult airway management. Sedative premedication may be helpful in patients with mild developmental delay.

Choanal atresia may account for respiratory distress. Difficult airway management may be encountered in patients with cleft lip and palate. Child may be uncooperative because of anxiety and mild mental retardation. Presence of congenital heart disease may require prophylactic antibiotics (endocarditis) and invasive hemodynamic monitoring.

Delayed puberty secondary to idiopathic hypogonadotropic hypogonadism, which is a diagnosis of exclusion, whereas anosmia and/or associated abnormalities are typical of Kallmann syndrome.