A novel variant in MAP3K7 associated with an expanded cardiospondylocarpofacial syndrome phenotype.

The transforming growth factor-beta-activated kinase 1 (TAK1) encoded by mitogen-activated protein kinase kinase kinase 7 (MAP3K7) is widely expressed and particpates in multiple molecular and cellular processes, including growth, differentiation, inflammation and apoptosis. Pathogenic variants in MAP3K7 have recently been associated with two disorders: cardiospondylocarpofacial syndrome (CSCFS) and frontometaphyseal dysplasia 2 (FMD2). To date, all small in-frame deletions and splice variants in MAP3K7 have been associated with CSCFS, while missense variants have been reported in both CSCFS and FMD2. Here, we present a patient with a novel heterozygous likely pathogenic variant in MAP3K7, c.125_127del, p.(Val42del), only the sixth variant associated with CSCFS to be described in the literature. Although this patient has a phenotype that is most consistent with that of CSCFS, including valvular heart disease, short stature, fusions of the spine and bones of the hands and feet, and certain facial dysmorphisms, he interestingly has some features reported previously in FMD2 but not CSCFS. These include flexion contractures of the elbow and widely spaced first and second toes, highlighting the overlap between these two syndromes. We additionally point out features in the patient presented here that are rare but recurrent amongst CSCFS patients previously reported in the literature, as well as a new distinctive cutaneous finding not previously reported.