Exploring the association between de novo mutations and non-syndromic cleft lip with or without palate based on whole exome sequencing of case-parent trios / 北京大学学报(医学版)

OBJECTIVE@#To explore the association between de novo mutations (DNM) and non-syndromic cleft lip with or without palate (NSCL/P) using case-parent trio design.@*METHODS@#Whole-exome sequencing was conducted for twenty-two NSCL/P trios and Genome Analysis ToolKit (GATK) was used to identify DNM by comparing the alleles of the cases and their parents. Information of predictable functions was annotated to the locus with SnpEff. Enrichment analysis for DNM was conducted to test the difference between the actual number and the expected number of DNM, and to explore whether there were genes with more DNM than expected. NSCL/P-related genes indicated by previous studies with solid evidence were selected by literature reviewing. Protein-protein interactions analysis was conducted among the genes with protein-altering DNM and NSCL/P-related genes. R package "denovolyzeR" was used for the enrichment analysis (Bonferroni correction: P=0.05/n, n is the number of genes in the whole genome range). Protein-protein interactions among genes with DNM and genes with solid evidence on the risk factors of NSCL/P were predicted depending on the information provided by STRING database.@*RESULTS@#A total of 339 908 SNPs were qualified for the subsequent analysis after quality control. The number of high confident DNM identified by GATK was 345. Among those DNM, forty-four DNM were missense mutations, one DNM was nonsense mutation, two DNM were splicing site mutations, twenty DNM were synonymous mutations and others were located in intron or intergenic regions. The results of enrichment analysis showed that the number of protein-altering DNM on the exome regions was larger than expected (P < 0.05), and five genes (KRTCAP2, HMCN2, ANKRD36C, ADGRL2 and DIPK2A) had more DNM than expected (P < 0.05/(2×19 618)). Protein-protein interaction analysis was conducted among forty-six genes with protein-altering DNM and thirteen genes associated with NSCL/P selected by literature reviewing. Six pairs of interactions occurred between the genes with DNM and known NSCL/P-related genes. The score measuring the confidence level of the predicted interaction between RGPD4 and SUMO1 was 0.868, which was higher than the scores for other pairs of genes.@*CONCLUSION@#Our study provided novel insights into the development of NSCL/P and demonstrated that functional analyses of genes carrying DNM were warranted to understand the genetic architecture of complex diseases.

Genetics of Autism Spectrum Disorder: Current Status and Possible Clinical Applications

Autism spectrum disorder (ASD) is one of the most complex behavioral disorders with a strong genetic influence. The objectives of this article are to review the current status of genetic research in ASD, and to provide information regarding the potential candidate genes, mutations, and genetic loci possibly related to pathogenesis in ASD. Investigations on monogenic causes of ASD, candidate genes among common variants, rare de novo mutations, and copy number variations are reviewed. The current possible clinical applications of the genetic knowledge and their future possibilities are highlighted.

Carrier detection in Duchenne muscular dystrophy using molecular methods.

Background & objectives: Duchenne and Becker muscular dystrophies are X-linked allelic disorders which are caused by mutations in the DMD gene. Carrier analysis in DMD is complicated due to the heterozygous nature of the X chromosome. Several techniques have been tried for carrier analysis in families where the mutation is identified including quantitative multiplex PCR (qmPCR), Southern blot, and now multiplex ligation-dependent probe amplification (MLPA). Linkage analysis is used in cases without identifiable mutations. The present study was undertaken to determine the status of probable carriers in families where the DMD deletion/duplication has been identified for the affected index cases. Methods: Carrier status was present in 150 probable carriers from 110 apparently unrelated families where the patients’ mutations were known. Of these 110 families, 100 were deletions, 9 duplications and 1 point mutation. Multiplex ligation-dependent probe amplification (MLPA) was used to assess the copy number changes and direct sequencing was used for the case with the point mutation. Results: Of the 150 cases, 49 were found to be carriers. Among the sporadic cases, it was observed that the rate of de novo mutations was very high (71%) as compared to the hereditary cases (29%), which was higher than the calculated rate (30%). It was observed that this difference was more apparent in deletion mutations than in duplications. Interpretation & conclusions: Identifying the DMD carrier rates in the families with unidentified deletions and duplications and where the causative mutation could be small insertions/deletions or point mutations could throw more light into this observation. MLPA was found to be useful in detecting copy number changes in DMD carriers and this could be the method of choice for DMD carrier analysis, when the mutation is detected in the affected child.

A novel deletion cluster at 13q14.2-q21.33 in an 80-year man with late onset leukemia: Clinical and molecular findings.

Chromosomal deletions are among the most common genetic events observed in hematologic malignancies; loss of genetic material is regarded as a hallmark of putative tumor suppressor gene localization. We have identified an unusual cluster of deletions at 13q14.2-13q21.33 in an 80-year-old father of a monozygotic twin pair discordant for schizophrenia, who developed chronic leukemia (CLL) at age 69. MATERIALS AND METHODS: The breakpoints for individual deletions in this cluster was identified by Affymetrix Human Array 6.0 screening. RESULTS: The deleted segments harbours a number of genes, most associated with cancer as well as a high concentration of LINEs, SINEs and related repeats. The derived chromosome represents an intra-chromosomal re-arrangement that quickly overtook blood progenitor cells probably before age 69 as a cause of CLL. CONCLUSIONS: The study highlights the role of ongoing de novo changes at susceptible sites, such as repeat rich regions, in the human genome. Also, it argues for the involvement of genes/deletions in the 13q(14.2-21.33) region in the development of CCL.