Kallmann Syndrome may be due to a number of mutations. One of the common causes is a mutation in KAL2, which often involves a monoallelic mutation.


Gene: FGFR1 (fibroblast growth factor receptor-1)

Gene location: 8p12


Inheritance: autosomal dominant with incomplete penetrance (parents and other family members often affected), However, almost a third of patients may have a de novo mutation.


Clinical features:

(1) variable loss of smell (no loss to anosmia)

(2) variable hypogonadism

(3) variable cleft palate

(4) tooth agenesis

(5) variable hearing impairment

(6) agenesis of the corpus callosum

(7) hypoplasia of the external ear

(8) absence of nasal cartilage

(9) bone anomalies in the hands and feet

(10) iris coloboma


Findings suggesting KAL1 (see previous section):

(1) bimanual synkinesis

(2) renal agenesis


Findings suggesting involvement of contiguous genes:

(1) severe anemia (involvement of ANK1)

(2) blindness (deletion at 8p11.2-12)


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