What causes Congenital anosmia ?
What causes congenital anosmia? Congenital anosmia may occur as an isolated abnormality or be associated with specific genetic disorders (such as Kallmann syndrome and congenital insensitivity to pain). Most cases of isolated congenital anosmia (not associated with additional symptoms) occur sporadically in people with no family history of the condition. In these people, the exact underlying cause of the condition is unknown. Most likely, there is more than one cause. Scientists suspect that the condition occurs due to abnormal development of the olfactory system (the sensory system used for sense of smell) prior to birth. This may include abnormalities of the nasal cavity, disruptions in the pathway that carries information from the nose to the brain, and/or malformations of the portion of the brain that processes sense of smell. Rarely, isolated congenital anosmia can affect more than one family member. This suggests that there may be a genetic component in some cases. One study found that some people affected by isolated congenital anosmia have changes (mutations) in PROKR2 or PROK2, two genes that have previously been reported in people with Kallmann syndrome (an inherited condition associated with congenital anosmia and other symptoms). To date, no other disease-causing genes have been identified.