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Familial Dysautonomia, is the result of mutations in IKBKAP gene on chromosome 9, which encodes for the IKAP protein ( IkB kinase complex associated protein ).

There have been three mutations in IKBKAP identified in individuals with FD.

The most common FD-causing mutation occurs in intron 20 of the donor gene.

Conversion of T --> C in intron 20 of the donor gene resulted in shift splicing that generates an IKAP transcript lacking exon 20.

Translation of this mRNA results in a truncated protein lacking all of the amino acids encoded in exons 20-37.

Another less common mutation is a G --> C conversion resulting in one amino acid mutation in 696, where Proline substitutes normal Arginine.

The decreased amount of functional IKAP protein in cells causes Familial Dysautonomia.