Identification of a novel splicing variant of IDS gene in a pedigree affected with type II glycosaminoglycan product storage disease / 中华医学遗传学杂志

OBJECTIVE@#To analyze variant of IDS gene in a pedigree affected with mucopolysaccharidosis type II (MPS II).@*METHODS@#The proband was subjected to next generation sequencing and Sanger sequencing to identify potential variants. Suspected variant was analyzed by its co-segregation with the disease in the pedigree. Its impact on mRNA splicing was analyzed by using reverse transcription PCR (RT-PCR).@*RESULTS@#A hemizygous IVS1-3T>G variant was found in the IDS gene in the proband. RT-PCR results revealed two abnormal cDNA fragments of 600 bp and 300 bp. The 600 bp fragment had inserted 216 nucleotides at the 3' end of intron 1, while the 300 bp fragment had lost 109 nucleotides at the 5' end of exon 2, which resulted in two truncated proteins comprising 38 and 92 amino acids, respectively, instead of the normal product (550 amino acids). The proband and his mother were respectively hemizygous and heterozygous for the variant. The same variant was not found among 100 normal controls.@*CONCLUSION@#The IVS1-3T>G variant of the IDS gene probably underlies the MPS II in this pedigree by causing reduction or elimination of the IDS protein.

Identification of a novel variant of COL4A5 gene in a pedigree affected with Alport syndrome / 中华医学遗传学杂志

OBJECTIVE@#To explore the genetic basis for a pedigree affected with Alport syndrome.@*METHODS@#Next generation sequencing and Sanger sequencing was carried out to detect potential variant of the COL4A5 gene among members from the pedigree and 100 unrelated healthy controls.@*RESULTS@#A novel missense c.3293G>T (p.Gly1098Val) variant was found in the COL4A5 gene among 6 affected members but not the unaffected members of the pedigree or the 100 healthy controls. According to the American College of Medical Genetics and Genomics standards and guidelines, the c.3293G>T variant was classified as pathogenic (PP1-strong+PM1+PM2+PP3+PP4).@*CONCLUSION@#By destructing the Gly-X-Y structure of its protein product, the c.3293G>T variant of the COL4A5 gene probably underlies the Alport syndrome in this pedigree. Above finding has enriched the spectrum of COL4A5 variants.

Novel mutations of XPC gene detected in a family affected with xeroderma pigmentosum group C / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To detect mutations of the XPC (XPC complex subunit, DNA damage recognition and repair factor) gene in a family affected with xeroderma pigmentosum group C (XP-C).</p><p><b>METHODS</b>The patient was subjected to next-generation sequencing and Sanger sequencing. Suspected mutations were validated by Sanger sequencing. Effect of splicing mutation was confirmed by reverse transcription-PCR (RT-PCR).</p><p><b>RESULTS</b>Compound heterozygous mutations of c.2098G to T and c.2034-7_2040del were found in the XPC gene in the proband. Among these, c.2098G to T (p.G700X) is a nonsense mutation resulting in a truncated XPC protein. C.2034-7_2040del involves the -1 position, which may alter the splice donor site of the intron 11 of XPC and result in a truncated XPC protein with loss of amino acids from 940 to 679 positions. The two mutations were not detected among 100 unrelated healthy controls.</p><p><b>CONCLUSION</b>Mutations of c.2098 G to T and c.2034-7_2040del of the XPC gene may lead to abnormal XPC expression and reduction or elimination of normal XPC functions, which may underlie the disease in this family.</p>

Application of droplet digital PCR for non-invasive prenatal diagnosis of single gene disease in two families / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To assess the value of droplet digital PCR (ddPCR) for non-invasive prenatal diagnosis of single gene disease in two families.</p><p><b>METHODS</b>Paternal mutation in cell-free DNA derived from the maternal blood and amniotic fluid DNA was detected by ddPCR. Suspected mutation in the amniotic fluid DNA was verified with Sanger sequencing.</p><p><b>RESULTS</b>The result of ddPCR and Sanger sequencing indicated that the fetuses have carried pathogenic mutations from the paternal side in both families.</p><p><b>CONCLUSION</b>Droplet digital PCR can accurately detect paternal mutation carried by the fetus, and it is sensitive and reliable for analyzing trace samples. This method may be applied for the diagnosis of single gene diseases caused by paternal mutation using peripheral blood sample derived from the mother.</p>

A novel mutation of GLI3 gene underlying synpolydactyly in a family / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To detect mutation of GLI3 gene in a family affected with autosomal dominant synpolydactyly.</p><p><b>METHODS</b>Genomic DNA was extracted from peripheral blood samples from members of the family and 100 unrelated healthy controls. Potential mutation was screened by next-generation sequencing and confirmed by Sanger sequencing.</p><p><b>RESULTS</b>A heterozygous frameshift mutation c.480dupC was identified in the GLI3 gene among all patients from the family. The same mutation was not found in unaffected family members and the 100 healthy controls.</p><p><b>CONCLUSION</b>The c.480dupC of the GLI3 gene probably underlies the synpolydactyly in this family.</p>