This allele corresponds to a substitution of G to A at coding nucleotide 2335 (transcript NM_018793), resulting in an amino acid substitution that replaces glutamic acid with lysine at position 779 (p.E779K). The missense mutation occurs at highly conserved APE motif of the Jak homology 2 (JH2) domain. Although mRNA transcript is detectable in spleen, anti-Tyk2 specific antibody cannot detect protein either in the activated or inactivated form. (J:85848)