The Correlation Study Of Phenotype And Genotype Of OI-Ⅸ And MPS-Ⅵ

A variety of genetic bone diseases are classified by International genetic bone disease in 2015.There are 436 kinds in 42 groups,dozens of which are common clinically.They are achondroplasia(ACH,MIM 100800),thanatophoric dysplasia(TD,MIM187600),hypochondroplasia(HCH,MIM 146000),pseudoachondroplasia(PSACH,MIM177170)and spondyloepiphyseal dysplasia tarda SEDT,MIM 271600),osteogenesis imperfecta(OI,MIM 166210),Mucopolysaccharidosis etc.Thus developing the molecular diagnosis including gene diagnosis and functional analysis is not only the important method to identify and diagnose these diseases but also a prerequisite for effective prenatal gene diagnosis.It is difficult to discriminate,even by imageology examination for they have similar clinical symptom.We detect two pathogenic mutations in PPIB and analyze the genotype-phenotype correlation in a Chinese family with OI-Ⅸ.We also detect one pathogenic mutation in ARSB and analyze the genotype-phenotype correlation in three Chinese families with MPS-Ⅵ.In this paper,the genetic diagnosis of osteogenesis Ⅸ and mucopolysaccharide Ⅵ were conducted in recent years,and a series of pathogenicity studies were conducted to reveal the correlation of phenotype and genotype,so as to create necessary precondition for prenatal,especially for preimplantation genetic diagnosis.Osteogenesis imperfecta(OI),also known as “brittle bone disease”,is one of the most common bone genetic disorders with increasing osteopsathyrosis,decreasing bone mass and variation of other collagenous tissues,most of which are autosomal dominant inheritance.In this paper,we did research on the gene diagnosis and functional analysis of two novel heterozygous PPIB mutations(father,c.25A>G;mother,c.509G>A)were identified in relation to osteogenesis imperfecta type IX.Next-generation sequencing(NGS)was used to screen the whole exome of the parents of proband.Screening of variation frequency,evolutionary conservation comparisons,pathogenicity evaluation,and protein structure prediction were conducted to assess the pathogenicity of the novel mutations such as MATN3、FGFR3、HSPG2、ACAN、PPIB.Several receptors,target genes and other antagonists were identified in the analysis,although no variations in these genes were detected.Among these potentially pathogenic genes,PPIB was the most probable candidate.Sanger sequencing was used to confirm the candidate variants.Real time Q-PCR was used to analyze the PPIB gene expression.Both mutations were predicted to be pathogenic by bioinformatics analysis and Real time Q-PCR analysis revealed down regulated PPIB expression in the two carriers.Mucopolysaccharidosis typeⅥ(MPS-Ⅵ)is a rare mucopolysaccharidosis disease.MPS-Ⅵ is a severely disabling,recessive genetic bone disease,metabolic disease,and the incidence of about 1/105.The pathological change of ARSB gene is the main cause of this disease,the coding gene encoding aromatic(Arylsulphatase)and the decomposition of intermediate Dermatan sulfate(DS)or Keratan sulfate(KS)and Heparan sulfate(CS),children are small,enlargement,splenomegaly,and polytrichia.According to the severity of the onset time and clinical symptoms,and the rate of the organ and disease involved,this disease can be divided into two heavy and heavy.Patients of MPS-Ⅵ with normal intelligence,the disease has not effective radical cure,bone marrow transplantation/hematopoietic stem cell transplantation is the risk of immune rejection,and high cost,the long-term effect is not clear;The effect of enzyme replacement therapy is good,but it is expensive and needs lifelong treatment.This shows that the etiology is the best strategy to prevent the disease,and then to carry out prenatal(or preimplantation)genetic diagnosis of high-risk fetus(or embryo).Explore the correlation of phenotypeand genotype of patients,and lay the foundation for future prevention and treatment,and accumulate valuable experience for TORCH work.To clarify the pathogenesis of mucopolysaccharidosis typeⅥ(MPS Ⅵ)and reveal the correlation between phenotype and genotype of MPS Ⅵ.The proband of family 1 was a compound heterozygous of c.943C>T and c.1197C>G.The proband of family 2 was also a compound heterozygous,carrying the c.523T>G/p.Y175D(a novel mutation from father)and c.1197C>G/ p.F399L(from mother).The amplification products of E2 and E3 of the proband of family3 failed to be obtained,but his parents had 400 bp and 459 bp specific bands.In this paper,it gains experience for conducting the future molecular genetic research on genetic bone diseases that we successfully made pathogenic gene study of the two bone diseases and prenatal gene diagnosis,which have an important significance in theory and practical application.