一个遗传性凝血因子Ⅴ缺乏症家系中凝血因子Ⅴ基因两种新突变的鉴定

目的对一个遗传性凝血因子Ⅴ缺乏症家系进行凝血因子Ⅴ（factorⅤ，FⅤ）基因突变的检测，探讨先天性凝血因子Ⅴ缺乏症的分子发病机理。方法PCR结合直接测序方法对先证者的FⅤ基因全部25个外显子及其旁侧序列进行分析，鉴别其中可能存在的基因变异。应用PCR产物反向测序法或PCR限制性内切酶分析技术对突变位点进行确证。随机选择100名健康体检者作为正常对照。结果先证者FⅤ基因存在两种突变，分别是第11外显子区的A1763C错义突变和位于第16内含子3′端剪接位点的G-T突变；家系分析表明这两个突变是双杂合子型，前者遗传自父亲，后者遗传自母亲。100名健康对照者均未发现A1763C错义突变。结论第11外显子A1763C错义突变和第16内含子3′端的剪接位点突变使先证者呈现双重杂合子型，可能是先证者FⅤ先天性缺乏的原因。     

Molecular bases of antithrombin deficiency: twenty-two novel mutations in the antithrombin gene

Antithrombin (AT) is a major physiological inhibitor of hemostasis. We report 22 novel antithrombin gene (SERPINC1) mutations associated with antithrombin deficiency in 17 French and five German families. They were all present at the heterozygous state. Nine missense mutations accounted for type I deficiency, defined by equally low antithrombin activity and antigen level. Most of them (7/9) affected highly conserved serpin residues and were associated with venous thrombosis occurring at a young age (before age 32). One splice site, one nonsense mutation, three small deletions and one insertion were also identified as a cause for type I antithrombin deficiency. Seven other missense mutations were identified in type II or unclassified AT deficiency; g.5270C>T (p.T147I, T115I) and g.5281A>T (p.I151F, I119F) change residues in the heparin binding region, g.13267C>G (p.P439A, P407A) and g.13271T>C (p.F440S, F408S) affect amino acids in the pleiotropic region, g.2372G>A (p.G25D, G-8D) changes a signal peptide amino acid, g.2456G>C (p.C53S, C21S) affects one of the three disulfide bonds of the protein, and g.7585A>T (p.M347K, M315K) changes a nonconserved residue on strand 2C.     

Asymptomatic factor VII deficiency in African Americans

African Americans with factor VII (FVII) deficiency, as defined by clinical laboratory values, are frequently asymptomatic. To date the genotypes underlying this FVII defect in asymptomatic African Americans have not been established. We show in 3 unrelated African-American patients that the defect is due to a G to A nucleotide change resulting in an arginine to glutamine mutation in Factor VII amino acid 304. This defect results in low FVII coagulant activity levels using rabbit brain thromboplastin but not using human thromboplastin. This report may aid transfusion and hematology specialists evaluate patient results and prevent unnecessary transfusions to treat patients with abnormal laboratory values.     

Functional studies of two novel and two rare mutations in the 21-hydroxylase gene

Congenital adrenal hyperplasia (CAH) is most commonly due to 21-hydroxylase deficiency and presents with a wide spectrum of clinical manifestations, from prenatal virilization and salt-wasting in the neonatal period to precocious pubarche and late-onset hyperandrogenic symptoms during adulthood. A limited number of mutations account for the majority of all mutated alleles, but a growing number of rare mutations are responsible for the disease in some patients. By sequence analysis of the CYP21A2 gene, we identified two novel (I171N and L446P) and two rare (R341P and R426H) mutations in seven Italian patients with CAH. One of the patients was diagnosed with mild non-classical CAH and was found to be a compound heterozygote (I171N/V281L), while all other patients showed severe phenotypes with latent or manifest salt-wasting. The residual activities measured after expression of the four mutant enzymes in COS-1 cells were all below 1% towards both natural substrates (17-OH-progesterone and progesterone) compared with the wild-type protein. All four mutations are, thus, associated with severe enzyme deficiency and are predicted to cause classic CAH if found in trans with other mutations causing severe enzyme deficiency.     

Identification of two novel mutations of the carnitine/acylcarnitine translocase (CACT) gene in a patient with CACT deficiency

Carnitine/acylcarnitine translocase (CACT) transports acylcarnitines into mitochondria in exchange for free carnitine, and is therefore an essential component within the fatty acid beta-oxidation pathway. CACT deficiency is an autosomal recessive disease caused by a mutation of the CACT gene. We have identified two novel mutations of the CACT gene in a patient with CACT deficiency. The first, a deletion mutation (146 del T), leads to premature termination and results in a very immature CACT protein. The second, a splicing mutation (261-10T>G), results in either skipping of exons 3 and 4, or of exon 3 alone, and leads to truncation of the protein. Each of these mutations is hypothesized to destroy the function of the CACT protein. We propose that each of these mutations of the CACT gene play a causative role in the disease. Received: August 9, 1999 / Accepted: October 14, 1999     

两个斑驳病家系KIT基因突变研究

目的 对2个斑驳病家系进行致病基因突变分析,为患者及其家系成员提供遗传咨询和生育指导.方法 分别采集家系1两例患者(先证者及其父亲)、家系2先证者及3名表型正常家系成员的外周血,提取外周血DNA和RNA.应用PCR、逆转录PCR及测序等技术,从基因组水平和表达水平对此两家系先证者和患者进行KIT基因诊断,并初步探讨检测到的突变对KIT基因功能的影响.结果 家系l中两例患者KIT基因均存在IVS12+ 2_+7delinsACATCTTTA的杂合突变,该突变在cDNA水平导致KIT基因c.1765-1779del突变,在氨基酸水平导致p.Gly592Ala/del:E12突变,使得KIT基因剪切位点发生改变,即其中一条cDNA第12外显子被跨越、未转录.家系2中先证者KIT基因存在c.2401A＞C突变,3位表型正常的家系成员未见该突变.结论 确诊了两个斑驳病家系的致病原因.家系1患者KIT基因均存在IVS12+ 2_+ 7delinsACATCTTTA的杂合突变,该突变为人类基因突变数据库未记载的、新的剪切突变;家系2先证者KIT基因存在c.2401A＞C突变,结合3位表型正常的家系成员KIT基因未见c.2401A＞C突变,推测该突变为先证者患斑驳病的致病突变可能性大.为此两家系进行遗传咨询和产前诊断提供了理论依据.     

Mutation pattern in clinically asymptomatic coagulation factor VII deficiency

A total of 122 subjects, referred after presurgery screening or checkup for prolonged prothrombin time, were characterized for the presence of coagulation factor VII deficiency. Fourteen subjects carried a partial and asymptomatic deficiency, and in half of them dysfunctional molecules were detected in plasma. In nine subjects we found five missense mutations differing from those previously found in factor VII deficient patients. The others were homozygous for a common polymorphism (R353Q) that affects factor VII levels. A new codon dimorphism (A330) was also found in exon 8. Four mutations (R223W, M298I, R304Q, and R353Q) located at FVII-specific residues point out protein regions that are important for coagulation factor evolution, and two mutations (G342E and E265K) affect generic or partially generic residues. The newly reported mutations were combined with those we previously found, totalling 17 independent mutations responsible for FVII deficiency in 27 Italian pedigrees. We observed several similarities with the mutation pattern determined in factor IX, which include a high percentage of transitions at CpG doublets, the presence of hot spot sites affected by multiple substitutions, and of several topologically equivalent mutations. © 1996 Wiley-Liss, Inc.     

Congenital factor VII deficiency: a case report

Factor VII deficiency is a rare congenital blood disorder. Its clinical features are rather variable and ranges from epistaxis to massive intracranial haemorrhage. Treatment involves replacement therapy, which constitutes use of fresh frozen plasma, prothrombin complex concentrates or recombinant activated factor VII. Although it is a rare entity, one still needs to consider it as a probable diagnosis in a newborn with coagulopathy. We report here a case of Factor VII deficiency in a newborn who presented with subdural haemorrhage at day 4 of life.     

Identification of two novel mutations in the OCRLI gene in Japanese families with Lowe syndrome

Kubota T, Sakurai A, Arakawa K, Shimazu M, Wakui K, Furihata K, Fukushima Y. Identification of two novel mutations in the OCRL1 gene in Japanese families with Lowe syndrome. Clin Genet 1998: 54: 199–202. 0 Munksgaard, 1998
The oculocerebrorenal syndrome of Lowe (OCRL) is a rare X-linked disorder with features of congenital cataracts. Fanconi syndrome of the renal tubule, and mental retardation. The OCRLI gene has been positionally cloned and shown to encode a phosphatidylinositol 4.5–biphos-phate-5–phosphatase. OCRL is thus thought to be an inborn error of inositol polyphosphate metabolism. We analyzed the gene in two Japanese OCRL patients and their families by DNA sequencing and mismatch polymerase chain reaction (PCR) followed by restriction digestion. A novel nonsense mutation (C1399T) replacing the glutamine of codon 391 (Gln 391 Stop) was identified in exon 12 in 1 patient and also in his mother. A novel missense mutation (C1743G) was identified in exon 15 in the second patient, his mother and maternal grandmother. The missense mutation predicts a substitution of serine for arginine (Ser 505 Arg) in a domain highly conserved among the inosi-tol-5–phosphatase family. Our observations expand the range of OCRLI mutations that cause Lowe syndrome. and will be useful for genetic counseling in these two Fdmilies.     

Functional relationships between three novel homozygous mutations in the ACTH receptor gene and familial glucocorticoid deficiency

Familial glucocorticoid deficiency (FGD) is an autosomal recessive disorder characterized by a glucocorticoid adrenal insufficiency without mineralocorticoid deficiency. Mutations of the ACTH receptor (MC2-R) gene have been reported in some FGD cases, but only a few of them have been functionally studied. We reported clinical features and MC2-R gene analysis in three families. For each proband, an homozygous mutation was identified after amplification and sequencing of the whole intronless MC2-R gene. One mutation converted Val-142 located in the second intracellular loop to Leu. Another mutation in the sixth transmembrane domain converted Ala-233 to Pro. The last mutation converted the negatively charged Asp-103 in the first extracellular loop to an uncharged Asn. Functional studies of these mutations as well as the S120R mutation were performed after stable transfection of M3 cells and measurement of ACTH-induced cAMP production. For the S120R, V142L, and A233P mutated MC2-R, cAMP production curves were similar to that obtained with M3 parental cells, confirming that these mutations are responsible for the FGD in the affected patients. The D103N-mutated MC2-R had an impaired cAMP response to physiological doses of ACTH, but the maximal response at very high concentrations of ACTH was similar to that obtained for the wild-type MC2-R. All these results demonstrated clear relationships based on functional studies between MC2-R homozygous mutations and FGD phenotype.     

Two novel mutations in the C7 gene in a Korean patient with complement C7 deficiency

Complement C7 deficiency is an autosomal recessive disorder well known to be associated with increased susceptibility to meningococcal infection and has mostly been reported in Caucasians. In the Korean population, no case of C7 deficiency has been reported to date. Recently we experienced an 11-yr-old girl with meningococcal meningitis who was diagnosed as having C7 deficiency based upon the undetectable serum C7 protein on radial immunodiffusion and the undetectable serum total and C7 hemolytic activities. To identify the genetic basis of the C7 deficiency of the patient, we performed a mutation analysis for the C7 gene and found two novel mutations; a point mutation at the 3'' splice acceptor site of intron 4 (c.281-1G>T) and a large deletion mutation encompassing almost the whole C7 gene from exon 1 to exon 17 (c.1-?_2350+?del). A haplotype analysis showed that the large deletion mutation was inherited from the patient''s father. To the best of our knowledge, this is the first confirmed case of C7 deficiency in Korea.     

两个新RUNX2基因突变引起家族性锁骨颅骨发育不全

Objective To identify the RUNX2 gene mutation in two unrelated Chinese families with cleidocranial dysplasia (CCD), and to assess the feasibility of gene diagnosis for patients with CCD. Methods Genomic DNA was isolated from peripheral blood samples of 4 patients and 4 healthy members in the two pedigrees as well as 102 unrelated healthy controls. All 7 coding exons and their flanking intronic sequences of the RUNX2 gene were amplified by PCR, then the PCR products were sequenced bi-directionally. The sequencing results were compared with normal sequences in GenBank to identify the mutation. The mutation was confirmed by RFLP with restriction endonuclease. Results In one family, a novel heterozygous missense mutation c. 346T＞A (W116R) in exon 1 of the RUNX2 gene was detected in the two affected individuals, and the mutation was further confirmed with Bsr Ⅰ restriction endonuclease digestion. In the other family, a novel nonsense mutation c. 610A＞T (K204X) was identified in the two patients. No above sequence change was found in the 102 healthy controls. Conclusion Two novel RUNX2 mutations were found in two unrelated Chinese families with cleidoeranial dysplasia. The identification of these mutations further extended the mutation spectrum of RUNX2 gene and will facilitate prenatal diagnosis and gene diagnosis of CCD.     

Mucopolysaccharidosis IVA within Tunisian patients: Confirmation of the two novel GALNS gene mutations

Mucopolysaccharidosis type IVA or Morquio A disease is an autosomal recessive disease resulting from a deficiency of the lysosomal enzyme N-acetylgalactosamine-6-sulfate-sulfatase, which hydrolyses N-acetylgalactosamine-6-sulfate and galactose-6-sulfate in glycosaminoglycans. Phenotypes in Morquio A disease vary from the classical form with severe bone dysplasia, heart valve involvement, corneal opacity, short trunk dwarfism and a life span of 20 to 30 years, to attenuated forms with normal life span, mild bone involvement and mild visceral organ involvement. Unlike the other forms of mucopolysaccharidoses, Morquio A disease is characterized by normal intelligence.