Abstract
Camptodactyly is a digit deformity characterized by permanent flexion contracture of one or both fifth fingers at the proximal interphalangeal joints. Though over 60 distinct types of syndromic camptodactyly have been described, only one disease locus (3q11.2-q13.12) for nonsyndromic camptodactyly has been identified. To identify the genetic defect for camptodactyly in a four-generation Chinese Han family, exome and Sanger sequencings were conducted and a missense variant, c.1016C>T (p.S339L), in the talin 2 gene (TLN2) was identified. The variant co-segregated with disease in the family and was not observed in 12 unaffected family members or 1,000 normal controls, suggesting that p.S339L is a pathogenic mutation. Two asymptomatic carriers in the family indicated incomplete penetrance or more complicated compensated mechanism. Most of p.S339L carriers also have relatively benign cardiac phenotypes. Expression of wild and mutant TLN2 in HEK293 cells suggested the predominant localization in cytoplasm. Our data suggest a potential molecular link between TLN2 and camptodactyly pathogenesis.
Highlights
(MIM 114200) is a digit deformity characterized by permanent flexion contracture of one or both fifth fingers at the proximal interphalangeal (PIP) joints
After excluding known variants identified in dbSNP132, 1000 genomes project, and HapMap with MAF >0.50%, there were 245 variants that were common among these four patients by exome sequencing
One variant co-segregated with the disease phenotype in this family: a C to T change in exon 9 (c.1016C>T), resulting in a p.S339L amino acid change in the talin 2 gene (TLN2) gene (NCBI Reference Sequence: NM_015059.2, NP_055874.2)
Summary
(MIM 114200) is a digit deformity characterized by permanent flexion contracture of one or both fifth fingers at the proximal interphalangeal (PIP) joints. Additional fingers might be affected, but the little finger is always involved [1]. It is a congenital hand disorder and the prevalence of camptodactyly is between 0.1% and 0.2% [2,3]. Camptodactyly is usually divided into three types. Type I is the most common, and camptodactyly is limited to the fifth finger. The abnormalities become apparent during infancy and affect boys and girls . Type II does not become apparent until preadolescence (ages 7 to 11 years) and affect
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