Genetic and functional analyses detect an EXT1 splicing pathogenic variant in a Chinese hereditary multiple exostosis (HME) family.

BACKGROUND: Hereditary multiple exostosis (HME) is an autosomal dominant skeletal disorder characterized by the development of multiple cartilage-covered tumors on the external surfaces of bones (osteochondromas). Most of HME cases result from heterozygous loss-of-function mutations in EXT1 or EXT2 gene. METHODS: Clinical examination was performed to diagnose the patients: Whole exome sequencing (WES) was used to identify pathogenic mutations in the proband, which is confirmed by Sanger sequencing and co-segregation analysis: qRT-PCR was performed to identify the mRNA expression level of EXT1 in patient peripheral blood samples: minigene splicing assay was performed to mimic the splicing process of EXT1 variants in vitro. RESULTS: We evaluated the pathogenicity of EXT1 c.1056 + 1G > T in a Chinese family with HME. The clinical, phenotypic, and genetic characterization of patients in this family were described. The variant was detected by whole-exome sequencing (WES) and confirmed by Sanger sequencing. Sequencing of the RT-PCR products from the patient's blood sample identified a large deletion (94 nucleotides), which is the whole exome 2 of the EXT1 cDNA. Splicing assay indicated that the mutated minigene produced alternatively spliced transcripts, which cause a frameshift resulting in an early termination of protein expression. CONCLUSIONS: Our study establishes the pathogenesis of the splicing mutation EXT1 c.1056 + 1G > T to HME and provides scientific foundation for accurate diagnosis and precise medical intervention for HME.

[ABO genotyping by duplex amplification and oligonucleotide arrays assay].

OBJECTIVE: ABO genotyping for forensic identification by oligonucleotide chip. METHODS: Oligonucleotide microarrays which could detect 3 different SNPs in exon 6 and exon 7 for ABO genotyping were used. Population studies on ABO was carried out in a sample of 115 unrelated Chinese Han individuals. The method was also applied to cases. RESULTS: The technique could identify 6 genotypes of ABO system. According to the results of population studies, no significant deviations from Hardy-Weinberg equilibrium could be found. The observed and expected heterozygosities were 0.591 and 0.616 respectively. The polymorphic information content was 0.544. The average exclusion probabilities in buos and trios was 0.188 and 0.344 respectively. The discrimination power is 0.777. CONCLUSION: The data and case application demonstrated that ABO typing by oligonucleotide probe arrays was a useful technique for paternity testing and individual identification.

[Evaluation on the number and value of STR loci applied in paternity identification].

OBJECTIVE: The study was carried out on the evaluation of number and value of STR loci applied in paternity identification. METHODS: A total of 13 STR loci, divided into four groups, was observed in 102 cases of paternity exclusion and 100 cases of paternity inclusion. PCR amplified products of 13 STR loci were injected into a capillary on the ABI PRISM 310 Genetic Analyzer. GeneScan software analyzed the collected data, which can then be imported into Genotyper software for genotyping of alleles. RESULTS: At least 3 STR loci incompatibilities between alleged father and child were found in all paternity exclusion cases of two observed groups which Cumulative Probability of Exclusion (CPE) was more than 99.99%, and in all paternity inclusion cases of those same observed groups, their Relative Chance of Paternity(RCP) could be over 99.99%. CONCLUSION: The exclusion of paternity should be based on at least three STR loci incompatibilities in the identification practice. As a criterion for evaluation of the number and value of STR loci applied in paternity test, CPE should reach 99.99%.