Molecular genetic analysis of mitochondrial DNA C1494T mutation in non-syndromic hearing loss of Chinese population / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To conduct a molecular epidemiological survey on the mitochondrial DNA C1494T mutation in non-syndromic hearing loss patients in Chinese population.</p><p><b>METHODS</b>Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) were used to screen the mitochondrial DNA 12S rRNA C1494T mutation in 20 patients with aminoglycoside antibiotic induced hearing loss, 136 sporadic non-syndromic hearing loss patients and 50 probands of pedigrees with non-syndromic hearing loss.</p><p><b>RESULTS</b>The C1494T mutation did not appear in all cases except for the positive control.</p><p><b>CONCLUSION</b>Incidence of mitochondrial DNA C1494T mutation is much lower than that of mitochondrial DNA A1555G mutation in non-syndromic hearing loss of Chinese population. Mitochondrial DNA C1494T mutation may be a rare variation in non-syndromic hearing loss and is not the main cause of aminoglycoside antibiotic induced-deafness.</p>

Phenotype heterogeneity associated with mitochondrial DNA A3243G mutation / 中国医学科学院学报

<p><b>OBJECTIVE</b>To discuss the clinical characteristics associated with mitochondrial DNA A3243G mutation.</p><p><b>METHODS</b>Clinical manifestations as well as results of brain CT and/or MRI scanning, blood level of lactic acid and muscle biopsy results of 25 mitochondrial encephalomyopathies patients whose A3243G mutations were analyzed.</p><p><b>RESULTS</b>Although all of the 25 patients carried mtDNA A3243G point mutation, their clinical manifestations varied greatly. Among them, there were 19 cases of mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS), 2 cases of encephalopathies which could not be classified into any specific type, 2 cases of floppy infants, one case of Kearns-Sayer syndrome (KSS) and one case of mitochondrial entero-myopathy. Most patients showed abnormal cranial radiological findings and ragged-red-fibers on muscle biopsies. Elevation of blood lactic acid was notably found in all of the 25 patients.</p><p><b>CONCLUSIONS</b>Significant variations in clinical manifestation and brain images are the prominent features in patients with A3243G mutation. Mitochondrial diseases should be considered in patients with multiple organ involvement and elevated serum lactic acid mtDNA mutation examination is necessary for the diagnosis of mitochondrial diseases.</p>

Five single nucleotide polymorphisms of casein kinase I gamma 2 gene in children with familial febrile convulsions / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To investigate the association between single nucleotide polymorphisms (SNPs) of casein kinase I gamma 2 (CSNK1G2) gene and children with familial febrile convulsions.</p><p><b>METHODS</b>The study samples were collected from unrelated Chinese Han population of Hebei province, including a cohort of 53 children with familial febrile convulsions(FC) and a control cohort of 101 individuals. Genotypes of SNPs rs2074882, rs740423, rs2277737, rs4806825, rs1059684 were typed by polymerase chain reaction-restriction fragment length polymorphism.</p><p><b>RESULTS</b>The frequencies of the five SNPs complied well with the Hardy-Weinberg equilibrium in FC group and normal group. The distribution of genotype and frequencies of alleles of the SNPs rs740423, rs2277737, rs1059684 in familial febrile convulsions group was significantly different from that in control group. No significant difference was observed in the distribution of genotypes and frequencies of alleles at SNP rs2074882 between two groups. Analysis on rs4806825 was not made owing to its less allele frequency.</p><p><b>CONCLUSION</b>These data indicate that SNPs rs740423, rs2277737, rs1059684 of CSNK1G2 gene may contribute to familial febrile convulsions in children.</p>

Detection of mtDNA 11778 (G-->A) point mutation in a family with Leber's hereditary optic neuropathy by site-specific polymerase chain reaction / 中国医学科学院学报

<p><b>OBJECTIVE</b>To find a simple, fast, accurate, and quantitative PCR-based method for mutation detection, so as to identify mitochondrial DNA 11778 G-->A point mutation in patients with Leber's hereditary optic neuropathy (LHON).</p><p><b>METHOD</b>On the basis of sequencing of mtDNA from LHON proband, M primer for mutation and N primer for normal were designed to be coupled with reverse primer respectively. Specific PCRs were done on an amplifying condition with high stringency such as a well controlled annealing temperature, low Mg2+ concentration and less thermal cycles. The objective pedigree includes 10 individuals, were against 40 normal control persons.</p><p><b>RESULTS</b>Different ratios of indicative mtDNA 11778A-->G mutation were checked out from the proband, affected maternal members and a 10 year-old boy (up to now no appearance yet), whereas not appeared on normal spouses, paternal offsprings in the family, neither did on 40 controls.</p><p><b>CONCLUSION</b>This site-specific PCR method is a kind of general mutation analysis way, without the restriction of existence of endonuclease site. It can be applied for the gene diagnosis of known-mutation hereditary diseases such as LHON.</p>