Mutated SASH1 promotes Mitf expression in a heterozygous mutated SASH1 knock‑in mouse model

Retyping and molecular pathology diagnosis of dyschromatosis universalis hereditaria

Dyschromatosis universalis hereditaria (DUH) is characterized by diffuse symmetrically distributed hypopigmented macules mixed with hyperpigmentation. DUH is divided into three types by Online Mendelian inheritance in man (OMIM) that is, DUH1 (OMIM 127500), DUH2 (OMIM 612715) and DUH3 (OMIM 615402) according to the different linkage regions. Although each condition possesses corresponding phenotypic characteristics and the prognosis for each is somewhat different, these disorders are highly overlapped and difficult to differentiate in the clinical setting. Our latest study reveals a novel DUH subtype that presents a mild phenotype of pigmentation anomalies and is named PER3rs772027021 SNP related DUH or DUH4 by us, which make the DUH subtype can be further retyped. Heterozygous distribution or mosaic-like distribution of melanin is a newly discovered pathological features that is uniquely demonstrated in the affected layers of DUH1 and DUH4 patients. In this review, DUH is further divided into four subtypes according the causative genes and their mutational sites, and the mutation regions described in the previous reports. To make an accurate diagnosis, we suggest that Sanger sequencing or the target region sequencing (TRS) to the candidate causative genes related melanogenesis may be the most effective and convenient method of clinical diagnosis or/and prenatal diagnosis for DUH and DUH-like patients. More importantly, heterozygous distribution or mosaic-like distribution of melanin can be utilized for differential diagnosis of DUH. We also investigate the underlying molecular mechanism to form mosaic-like melanin in the affected layers of hyper- and/or hypo-pigmented macules from DUH1 and DUH4 patients. This review provides a molecular and pathological delineation of four types of DUH and aims to establish a concise diagnostic strategy to allow clinical dermatologists to make an accurate diagnosis.

The emerging and diverse roles of the SLy/SASH1-protein family in health and disease-Overview of three multifunctional proteins

Intracellular adaptor proteins are indispensable for the transduction of receptor-derived signals, as they recruit and connect essential downstream effectors. The SLy/SASH1-adaptor family comprises three highly homologous proteins, all of them sharing conserved structural motifs. The initial characterization of the first member SLy1/SASH3 (SH3 protein expressed in lymphocytes 1) in 2001 was rapidly followed by identification of SLy2/HACS1 (hematopoietic adaptor containing SH3 and SAM domains 1) and SASH1/SLy3 (SAM and SH3 domain containing 1). Based on their pronounced sequence similarity, they were subsequently classified as one family of intracellular scaffold proteins. Despite their obvious homology, the three SLy/SASH1-members fundamentally differ with regard to their expression and function in intracellular signaling. On the contrary, growing evidence clearly demonstrates an important role of all three proteins in human health and disease. In this review, we systematically summarize what is known about the SLy/SASH1-adaptors in the field of molecular cell biology and immunology. To this end, we recapitulate current research about SLy1/SASH3, SLy2/HACS1, and SASH1/SLy3, with an emphasis on their similarities and differences.

Novel missense mutation of SASH1 in a Chinese family with dyschromatosis universalis hereditaria

BACKGROUND

Dyschromatosis universalis hereditaria (DUH) is a pigmentary dermatosis characterized by generalized mottled macules with hypopigmention and hyperpigmention. ABCB6 and SASH1 are recently reported pathogenic genes related to DUH, and the aim of this study was to identify the causative mutations in a Chinese family with DUH.

METHODS

Sanger sequencing was performed to investigate the clinical manifestation and molecular genetic basis of these familial cases of DUH, bioinformatics tools and multiple sequence alignment were used to analyse the pathogenicity of mutations.

RESULTS

A novel missense mutation, c.1529G>A, in the SASH1 gene was identified, and this mutation was not found in the National Center for Biotechnology Information Database of Short Genetic Variation, Online Mendelian Inheritance in Man, ClinVar, or 1000 Genomes Project databases. All in silico predictors suggested that the observed substitution mutation was deleterious. Furthermore, multiple sequence alignment of SASH1 revealed that the p.S510N mutation was highly conserved during evolution. In addition, we reviewed the previously reported DUH-related gene mutations in SASH1 and ABCB6.

CONCLUSION

Although the affected family members had identical mutations, differences in the clinical manifestations of these family members were observed, which reveals the complexity of the phenotype-influencing factors in DUH. Our findings reveal the mutation responsible for DUH in this family and broaden the mutational spectrum of the SASH1 gene.