Demirdas, Serwet

Mitogen-Activated Protein 3 Kinase 7 (MAP3K7, MIM 602614) encodes the ubiquitously expressed transforming growth factor β (TGF-β)–activated kinase 1 (TAK1), which plays a crucial role in many cellular processes. Variants in the MAP3K7 gene have been linked to 2 distinct disorders: frontometaphyseal dysplasia type 2 (FMD2, MIM #617137) and cardiospondylocarpofacial syndrome (CSCF, MIM #157800). The fact that different variants can induce 2 distinct phenotypes suggests a phenotype/genotype correlation, but no side-by-side comparison has been done thus far to confirm this. Here we significantly expand the cohort and the description of clinical phenotypes for individuals with CSCF and FMD2 who carry variants in MAP3K7. We show that in contrast to FMD2-causing variants, CSCF-causing variants in MAP3K7 have a loss-of-function effect. Additionally, patients with pathogenic variants in MAP3K7 are at risk for cardiac disease, have symptoms associated with connective tissue disease and we show overlap in clinical phenotypes of CSCF with Noonan syndrome. Together, we provide evidence for a molecular fingerprint of FMD2- versus CSCF-causing MAP3K7 variants and conclude that variants in MAP3K7 should be considered in the differential diagnosis of patients with syndromic congenital cardiac defects and/or cardiomyopathy, syndromic connective tissue disorders and in the differential diagnosis of Noonan syndrome.

AbstractThe study aimed at widening the clinical and genetic spectrum of ASXL3‐related syndrome, a neurodevelopmental disorder, caused by truncating variants in the ASXL3 gene. In this international collaborative study, we have undertaken a detailed clinical and molecular analysis of 45 previously unpublished individuals with ASXL3‐related syndrome, as well as a review of all previously published individuals. We have reviewed the rather limited functional characterization of pathogenic variants in ASXL3 and discuss current understanding of the consequences of the different ASXL3 variants. In this comprehensive analysis of ASXL3‐related syndrome, we define its natural history and clinical evolution occurring with age. We report familial ASXL3 pathogenic variants, characterize the phenotype in mildly affected individuals and discuss nonpenetrance. We also discuss the role of missense variants in ASXL3. We delineate a variable but consistent phenotype. The most characteristic features are neurodevelopmental delay with consistently limited speech, significant neuro‐behavioral issues, hypotonia, and feeding difficulties. Distinctive features include downslanting palpebral fissures, hypertelorism, tubular nose with a prominent nasal bridge, and low‐hanging columella. The presented data will inform clinical management of individuals with ASXL3‐related syndrome and improve interpretation of new ASXL3 sequence variants.