Four Genetic Bone Disease Gene Diagnosis And Prenatal Diagnosis

Constitutional bone disease are a large and disparate group of diseases whose unifying features are malformation, disproportionate growth, and deformation of the skeleton or of individual bones. This study try to research SEDT, ACH, osteogenesis imperfecta(OI) and spondylepiphyseal dysplasia congenita(SEDC), detecting the virulence gene based on the identify of clinic diagnosis and to provide practical diagnostic help.This study divided into three parts:Part 1:To report a new case of a five-generation Chinese SEDT family with 6 affected individuals. Molecular genetics research found a new mutation site, abundant the genetic map and investigate the potential mechanism of variable splicing.Methods:Polymerase chain reaction, reverse transcription-polymerase chain reaction (RT-PCR), DNA and cDNA sequencing of SEDL gene were performed to analyze the disease-causing mutation.Results:All patients'and carriers had a single nucleotide mutation(c.61 G>T, p,Glu21stop) in exon3 of SEDL gene. Interestingly, RT-PCR results showed that all the parents'and carriers had two transcripts, the longer had the normal size, the shorter skipped the exon3 (c.-19-c.93 del).Conclusion: The mutation of SEDL gene(c.61 G>T) is a new mutation site, the detailed clinical and molecular genetics research abundant the genetic map. SEDL gene c.61 G>T(p.Glu21stop) mutation may activate the potential variable splicing regulation components. The selectively splicing of mRNA induce the skipping of exon3 and generate a new ranscription. The specific mechanism need to research deeply.Part 2:To report three sporadic achondroplasia cases, the phenotype is characterized by rhizomelic disproportionate short stature, short hands and lordotic lumbar spine.Methods:PCR and DNA sequencing of FGFR3 gene were performed to analyze the disease-causing mutation.Results:All 3 patients'had a single nucleotide mutation(c.1138 G>A) of FGFR3 gene, which induce the transformation of amino acid (Gly380Cys).Conclusion: All of the three sporadic achondroplasia parents had the same mutation (c.1138 G>A). This is conduce to diagnosis the achondroplasia, and can prevent the birth of achondroplasia fetus. Part 3:To research the gene diagnosis and prenatal molecular diagnosis induced by collagen gene COL1A1 and COL2A1 mutations. To screen the mutation site of a OI case. OI is a relatively common hereditary connective tissue disorder characterized by bone fragility and fractures. Otherwise, proceed prenatal molecular diagnosis for one gravida in a family with SEDC caused by G504S mutation of COL2A1 gene.Methods:PCR and DNA sequencing of COL1A1 gene were performed to analyze the disease-causing mutation. Select three polymorphic STR sites to evacuate maternal cell contamination. Direct sequencing of the samp leswere performed after amplifying exon23 of COL2A1 containing the potential mutation.Results:The COL1A1 gene of the OI parent had a single nucleotide mutation(c.3263 G>A, p.Gly1088Glu). However, his parents, sister and 250 controls were not carried this mutation.. Sequncing analysis revealed the fetus did not show the mutation of COL2A1 gene. The prenatal diagnosis result of the fetus was consistent with the sonographic scan.Conclusion: The COL1A1 gene c.3263 G>A mutation induce the synthetic triple-helical oligopeptide with a Gly to Glu substitution. The genotype of the fetus who had prenatal molecular diagnosis was normal, they had a mormal daughter eventually.