A TNNI2 mutation in a family with distal arthrogryposis type 2B.

Linkage mapping in a three-generation family with a distal arthrogryposis (DA) phenotype intermediate between DA2A and DA1 indicated linkage to 11p15.5 but not 9p13. Follow up DNA sequencing of the TNNI2 gene detected a three base pair deletion that would be predicted to result in the deletion of a glutamic acid at codon position 167 (DeltaE167). This mutation, like the two previously described TNNI2 mutations, is located in the carboxy-terminal domain and thus supports the existence of a TNNI2 critical region sensitive to alteration that will give rise to DA. Physical examination of family members confirms the high degree of variability in expression amongst mutation carriers.