CD20, the high-affinity IgE receptor beta chain (FcepsilonRIbeta), and HTm4 are structurally related cell surface proteins expressed by hematopoietic cells. Recently, 16 novel human and mouse genes were identified that encode new members of this nascent protein family that we have named the membrane-spanning 4A gene family, with at least 12 subgroups (MS4A1-MS4A12). In the current study, we identified three additional human MS4A genes: MS4A4E, MS4A6E, and MS4A10. All family members have at least four potential transmembrane domains and N- and C-terminal cytoplasmic domains encoded by distinct exons, except MS4A6E which contains two transmembrane domains. Otherwise, the 12 currently identified MS4A genes share common structural features and similar intron/exon splice boundaries, and are clustered along an approximately 600-kb region of Chromosome 11q12. In contrast to other MS4A genes, MS4A4E, MS4A6E, and MS4A10 transcripts were rare and not detected among hematopoietic cells and most nonlymphoid tissues. Sequence polymorphisms were identified in the MS4A6E gene and common splice variants were observed for the MS4A4A, MS4A5, MS4A6A, and MS4A7 genes. Thus, the MS4A family currently includes 24 distinct human and mouse genes. Like CD20 and FcepsilonRIbeta, the 10 other human MS4A family members are likely to be components of oligomeric cell surface complexes involved in signal transduction in diverse cell lineages.

Summary Mutation of the non‐muscle myosin heavy chain type II‐A results in MYH9‐related hereditary macrothrombocytopenia (HMTC), including four autosomal dominant platelet disorders: May‐Hegglin anomaly (MHA), Sebastian (SBS), Fechtner (FS) and Epstein (EPS) syndrome. Denaturing high‐performance liquid chromatography (DHPLC) was optimised for rapid screening of the seven exons harbouring all but one of the previously reported mutations of MYH9. Individuals from 13 families with phenotypes suggestive of MYH9‐related HMTC were screened for mutations by DHPLC followed by direct sequencing of samples with aberrant column retention time. Mutations were identified in all 13 families. Six distinct missense heterozygous mutations were found in 10 families, including six families with MHA or SBS (E1841K, D1424N), three families with FS (R702H, R1165C, and D1424Y), and one family with EPS (S96L). A truncating mutation (R1933X) was found in three MHA families. A review of all published mutations suggests that mutation in the C‐terminal coiled coil region or truncation of the tailpiece is associated with haematological‐only phenotype, while mutation of the head ATPase domain frequently is associated with nephropathy and/or hearing loss. Mutations of other regions have intermediate expression of non‐haematological characteristics. Further study is required to confirm these associations and understand the molecular basis for this genotype–phenotype relationship.

The Consortium for Mouse Cell Line Authentication was formed to validate Short Tandem Repeat (STR) markers for intraspecies identification of mouse cell lines. The STR profiling method is a multiplex polymerase chain reaction (PCR) assay comprised of primers targeting 19 mouse STR markers and two human STR markers (for interspecies contamination screening). The goals of the Consortium were to perform an interlaboratory study to–(1) validate the mouse STR markers to uniquely identify mouse cell lines (intraspecies identification), (2) to provide a public database of mouse cell lines with the National Institute of Standards and Technology (NIST)-validated mouse STR profiles, and (3) to publish the results of the interlaboratory study. The interlaboratory study was an international effort that consisted of 12 participating laboratories representing institutions from academia, industry, biological resource centers, and government. The study was based on 50 of the most commonly used mouse cell lines obtained from the American Type Culture Collection (ATCC). Of the 50 mouse cell lines, 18 had unique STR profiles that were 100% concordant (match) among all Consortium laboratory members, and the remaining 32 cell lines had discordance that was resolved readily and led to improvement of the assay. The discordance was due to low signal and interpretation issues involving artifacts and genotyping errors. Although the total number of discordant STR profiles was relatively high in this study, the percent of labs agreeing on allele calls among the discordant samples was above 92%. The STR profiles, including electropherogram images, for NIST-validated mouse cell lines will be published on the NCBI BioSample Database ( https://www.ncbi.nlm.nih.gov/biosample/ ). Overall, the interlaboratory study showed that the multiplex PCR method using 18 of the 19 mouse STR markers is capable of discriminating at the intraspecies level between mouse cell lines. Further studies are ongoing to refine the assay including (1) development of an allelic ladder for improving the accuracy of allele calling and (2) integration of stutter filters to identify true stutter.