Investigation Of Disease Causative Mutations In Multi Pedigrees With Mendelian Inherited Diseases

Mendelian inherited diseases are diseases caused by a single gene or genomic element change in the DNA sequence. Pedigrees with the same disease could be caused by different genes. We have got three pedigrees with inherited diseases. And we investigated the causative genes and mutations by multiple technologies.As for EBMD （Epithelial Basement Membrane Dystrophy）, previous researches have reported gene TGFBI is the causative gene in the pedigree. We sequenced the TGFBI gene’s coding DNA sequences in two patients’ samples. We found a novel damaging SNV （chr5:135420318_C/A, NCBI36/hg18）. SNV prediction revealed that this nucleotide change could cause damaging amino acid change （Thr538Lys） to the protein. After sequencing all the samples’ TGFBI sequences, we found that all the patients with EBMD and one healthy person IV₇had the novel damaging SNV. Given the late onset of EBMD and previous report, we reached a conclusion that in this pedigree TGFBI was the causative gene for EBMD, and IV₇would be a patient in the future.As for pedigree with FECD （Fuchs Endothelial Corneal Dystrophy） and vitiligo, a lot of candidate genes were reported by previous researches. We chose four samples for whole exome capture and sequencing. After the analysis and validation of126SNV and Indel, we did not found a candidate variant for FECD. As for vitiligo, we found novel nonsynonymous SNVs that appeared in all the case samples and some healthy samples in the pedigree. Because the range of vitiligo onset age in this family is from35to55, we cannot determine the real situation of the healthy samples with the SNVs, and one of these SNVs could be the causative variant for vitiligo in this pedigree. Meanwhile, we did the whole genome typing in the family; Due to the lack of enough well-phenotyped samples, no conclusion was reached from the linkage analysis and the CNV analysis of the family. In the future, considering the lack of reads depth, we need to sequence samples with new capture and sequencing platform and find the causative gene and mutation for FECD.As for neuromyotonia, previous researches have reported genes KCNA1, KCNQ2and KCNQ3were involved in the disease. We amplified and sequenced the three candidate genes’coding DNA sequences of sample11116. No novel nonsynonymous SNV/Indel was discovered. We had sequenced two patients’ whole exome. After data analysis, no SNVs/Indels were verified to be coseparated with the neuromyotonia in the pedigree. Whole genome typing was performed in16samples. Linkage analysis found that there were linkage regions with high LOD score, which meant there might be SNV/Indel involved with neuromyotonia in the noncoding DNA region. Next, we consider sequencing the linkage regions with high LOD score, and hope to find the causative SNV/Indel of neuromyotonia.