Mutation analysis and prenatal diagnosis of families affected with Duchenne and Becker muscular dystrophy / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To detect potential mutations for probands from families affected with Duchenne/Becker muscular dystrophy (DMD/BMD), and to carry out prenatal diagnosis through identification of female carriers.</p><p><b>METHODS</b>A total of 43 DMD/BMD families were recruited. Multiplex PCR was used to analyze 18 exons within hotspots for DMD gene deletions. Multiplex ligation-dependent probe amplification (MLPA) was used to detect potential deletions and duplications of DMD gene for 43 patients and 36 females from 32 families. Prenatal diagnosis was performed for 27 families.</p><p><b>RESULTS</b>Deletional mutations were detected in 26 patients with multiplex PCR. In addition, MLPA has detected 3 deletions and 6 duplicational mutations, and the ranges of mutations were all determined. Among 36 female members, 18 were determined as carriers of deletional mutations, 10 were excluded as mutation carriers. The status of remaining 8 could not be determined. For prenatal diagnosis, 3 out of 18 male fetuses were diagnosed as patients and 1 female fetus was identified as carrier.</p><p><b>CONCLUSION</b>MLPA is an accurate and reliable method for detecting deletional/duplicational mutations of DMD gene as well as for prenatal diagnosis and detection of female carriers.</p>

Mutation analysis and prenatal diagnosis of EXT1 gene mutations in Chinese patients with multiple osteochondromas / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Multiple osteochondromas (MO), an inherited autosomal dominant disorder, is characterized by the presence of multiple exostoses on the long bones. MO is caused by mutations in the EXT1 or EXT2 genes which encode glycosyltransferases implicated in heparin sulfate biosynthesis.</p><p><b>METHODS</b>In this study, efforts were made to identify the underlying disease-causing mutations in patients from two MO families in China.</p><p><b>RESULTS</b>Two novel EXT1 gene mutations were identified and no mutation was found in EXT2 gene. The mutation c.497T > A in exon 1 of the EXT1 gene was cosegregated with the disease phenotype in family 1 and formed a stop codon at amino acid site 166. The fetus of the proband was diagnosed negative. In family 2, the mutation c.1430-1431delCC in exon 6 of the EXT1 gene would cause frameshift and introduce a premature stop codon after the reading frame being open for 42 amino acids. The fetus of this family inherited this mutation from the father.</p><p><b>CONCLUSIONS</b>Mutation analysis of two MO families in this study demonstrates its further application in MO genetic counseling and prenatal diagnosis.</p>

Molecular genetic study of MECP2 gene for a patient with typical Rett syndrome / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To provide genetic diagnosis and counseling for a 2-year-old girl with typical Rett syndrome through analyzing the methyl-CpG binding protein 2 (MECP2) gene.</p><p><b>METHODS</b>Potential mutation of the MECP2 gene was screened by DNA sequencing and multiplex ligation-dependent probe amplification (MLPA) analysis of members of the family as well as normal controls. Lymphocyte culture for karyotype analysis was carried out for the patient to exclude chromosomal abnormalities.</p><p><b>RESULTS</b>The karyotype of the girl was normal. No variation of the MECP2 gene was detected in the patient by direct sequencing. A heterozygosis variation, c.1072G>A in exon 4 of the MECP2 gene was detected in a normal female control, which was not found in other controls. The son and daughter of the female control were respectively heterozygous and homozygous carriers of the same mutation. By MLPA analysis, a heterozygosis deletion of exon 3 and part of exon 4 was detected in the patient. cDNA amplification and sequencing confirmed the presence of a 1176 bp deletion (c.27-1202del1176). The same deletion was not detected in the parents.</p><p><b>CONCLUSION</b>A large deletion in MECP2 gene was detected with MLPA in a patient featuring typical Rett syndrome. The same deletion was missed by sequencing analysis. With cDNA sequencing, the breakage point of the mutation can be mapped precisely.</p>

Mutational analysis in a family with X-linked spondyloepiphyseal dysplasia tarda / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To detect the mutation of the SEDL gene in an X-linked spondyloepiphyseal dysplasia tarda (SEDL) family.</p><p><b>METHODS</b>Two patients and three females of the X-SEDL family were detected using reverse transcriptase PCR (RT-PCR) and sequence analysis.</p><p><b>RESULTS</b>A G209A mutation of SEDL gene was detected in the cDNA sequences of the patients, which was confirmed by sequence analysis of the exon 4 of the SEDL gene. The daughter of the proband was a carrier of the mutation.</p><p><b>CONCLUSION</b>Since the SEDL gene is relatively small, sequence analysis of cDNA of the SEDL gene was possible after extraction of total RNA followed by RT-PCR. Mutations in the open reading frame can be detected y by cDNA sequencing. It was relatively more rapid and direct than amplifying and detecting the exons one by one.</p>

Prenatal gene diagnosis of oculocutaneous albinism type I / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>Mutation analysis and prenatal gene diagnosis for the mutated tyrosinase (TYR) gene in two families with oculocutaneous albinism type I (OCA1).</p><p><b>METHODS</b>To define the fetus genotypes and gene mutation sites, the PCR and sequencing techniques were applied to amplify and analyze the regions of exon, exon-intron and promoter of TYR gene in probands and their parents of 2 families.</p><p><b>RESULTS</b>The patient or proband of family 1 showed as a compound heterozygote with mutants R278X and 929insC. However, the fetus did not get any one of the two mutations, and so was with a normal genotype and phenotype. The parents of proband in family 2 were heterozygous with IVS4+ 3A>T or G253E respectively, but their fetus was heterozygous only with IVS4+3A>T but without G253E, and so was a carrier as his father.</p><p><b>CONCLUSION</b>In the mainland of China, the prenatal gene diagnosis of OCA1 is reported for the first time.</p>

A novel P gene mutation in a Chinese family with oculocutaneous albinism / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To investigate gene mutations of a consanguineous family with two oculocutaneous albinism (OCA) patients.</p><p><b>METHODS</b>Genomic DNA was prepared from peripheral leukocytes. All of the exons and flanking introns of P gene and TYR gene were PCR-direct-sequenced. Hha I restriction fragment length polymorphism in codon 787 of the P gene was studied in the family and 102 unrelated normal Chinese individuals.</p><p><b>RESULTS</b>Although no mutations were found in TYR gene, a missense mutation A787T was found in P gene. Two patients of the family were both homozygous for A787T. Their parents and brother were heterozygous for the mutation. The mutation was not observed among 102 normally pigmented subjects.</p><p><b>CONCLUSION</b>The A787T mutation is not a common polymorphism among normal Chinese and it seems most likely to be a pathological OCA2 mutation. This is the first report on the study of gene diagnosis in Chinese OCA2 patients.</p>