Costello syndrome is a multiple congenital anomaly and mental retardation syndrome characterized by coarse face, loose skin, cardiomyopathy and predisposition to tumors. We identified four heterozygous de novo mutations of HRAS in 12 of 13 affected individuals, all of which were previously reported as somatic and oncogenic mutations in various tumors. Our observations suggest that germline mutations in HRAS perturb human development and increase susceptibility to tumors.
By exome sequencing, we found de novo SMARCB1 mutations in two of five individuals with typical Coffin-Siris syndrome (CSS), a rare autosomal dominant anomaly syndrome. As SMARCB1 encodes a subunit of the SWItch/Sucrose NonFermenting (SWI/SNF) complex, we screened 15 other genes encoding subunits of this complex in 23 individuals with CSS. Twenty affected individuals (87%) each had a germline mutation in one of six SWI/SNF subunit genes, including SMARCB1, SMARCA4, SMARCA2, SMARCE1, ARID1A and ARID1B.
RAS GTPases mediate a wide variety of cellular functions, including cell proliferation, survival, and differentiation. Recent studies have revealed that germline mutations and mosaicism for classical RAS mutations, including those in HRAS, KRAS, and NRAS, cause a wide spectrum of genetic disorders. These include Noonan syndrome and related disorders (RAS/mitogen-activated protein kinase [RAS/MAPK] pathway syndromes, or RASopathies), nevus sebaceous, and Schimmelpenning syndrome. In the present study, we identified a total of nine missense, nonsynonymous mutations in RIT1, encoding a member of the RAS subfamily, in 17 of 180 individuals (9%) with Noonan syndrome or a related condition but with no detectable mutations in known Noonan-related genes. Clinical manifestations in the RIT1-mutation-positive individuals are consistent with those of Noonan syndrome, which is characterized by distinctive facial features, short stature, and congenital heart defects. Seventy percent of mutation-positive individuals presented with hypertrophic cardiomyopathy; this frequency is high relative to the overall 20% incidence in individuals with Noonan syndrome. Luciferase assays in NIH 3T3 cells showed that five RIT1 alterations identified in children with Noonan syndrome enhanced ELK1 transactivation. The introduction of mRNAs of mutant RIT1 into 1-cell-stage zebrafish embryos was found to result in a significant increase of embryos with craniofacial abnormalities, incomplete looping, a hypoplastic chamber in the heart, and an elongated yolk sac. These results demonstrate that gain-of-function mutations in RIT1 cause Noonan syndrome and show a similar biological effect to mutations in other RASopathy-related genes.
The Great East Japan Earthquake (GEJE) and resulting tsunami of March 11, 2011 gave rise to devastating damage on the Pacific coast of the Tohoku region. The Tohoku Medical Megabank Project (TMM), which is being conducted by Tohoku University Tohoku Medical Megabank Organization (ToMMo) and Iwate Medical University Iwate Tohoku Medical Megabank Organization (IMM), has been launched to realize creative reconstruction and to solve medical problems in the aftermath of this disaster. We started two prospective cohort studies in Miyagi and Iwate Prefectures: a population-based adult cohort study, the TMM Community-Based Cohort Study (TMM CommCohort Study), which will recruit 80 000 participants, and a birth and three-generation cohort study, the TMM Birth and Three-Generation Cohort Study (TMM BirThree Cohort Study), which will recruit 70 000 participants, including fetuses and their parents, siblings, grandparents, and extended family members. The TMM CommCohort Study will recruit participants from 2013 to 2016 and follow them for at least 5 years. The TMM BirThree Cohort Study will recruit participants from 2013 to 2017 and follow them for at least 4 years. For children, the ToMMo Child Health Study, which adopted a cross-sectional design, was also started in November 2012 in Miyagi Prefecture. An integrated biobank will be constructed based on the two prospective cohort studies, and ToMMo and IMM will investigate the chronic medical impacts of the GEJE. The integrated biobank of TMM consists of health and clinical information, biospecimens, and genome and omics data. The biobank aims to establish a firm basis for personalized healthcare and medicine, mainly for diseases aggravated by the GEJE in the two prefectures. Biospecimens and related information in the biobank will be distributed to the research community. TMM itself will also undertake genomic and omics research. The aims of the genomic studies are: 1) to construct an integrated biobank; 2) to return genomic research results to the participants of the cohort studies, which will lead to the implementation of personalized healthcare and medicine in the affected areas in the near future; and 3) to contribute the development of personalized healthcare and medicine worldwide. Through the activities of TMM, we will clarify how to approach prolonged healthcare problems in areas damaged by large-scale disasters and how useful genomic information is for disease prevention.
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