A novel MAP3K7 splice mutation causes cardiospondylocarpofacial syndrome with features of hereditary connective tissue disorder

Heterozygous variants in MAP3K7 , encoding the transforming growth factor-β-activated kinase 1 (TAK1), are associated with the ultrarare cardiospondylocarpofacial syndrome (CSCFS). Specific gain-of-function variants in the same gene cause the allelic frontometaphyseal dysplasia type 2. Phenotypic series of frontometaphyseal dysplasia also comprise variants in FLNA (type 1) and two patients with a heterozygous variant in TAB2 (type 3). We report on a 7-year-old girl with CSCFS due to the novel heterozygous c.737-7A>G variant in MAP3K7 . The identified variant generates a new splice acceptor site causing an in-frame insertion of 2 amino acid residues (p.Asn245_Gly246insValVal), as demonstrated by RNA study. The patient was originally ascertained for a presumed hereditary connective tissue disorder due to soft/dystrophic skin, extreme joint hypermobility, polyvalvular heart disease, and upper gastrointestinal dismotility. Our study confirms locus homogeneity for CSCFS, expands the mutational spectrum of MAP3K7 , and adds data on the existence of a community of connective tissue disorders caused by abnormalities of the TAK1-dependent signaling pathway.