Rapid detection of a point mutation in thyroid-stimulating hormone beta-subunit gene causing congenital isolated thyroid-stimulating hormone deficiency.

Previous study showed that congenital isolated TSH deficiency in Japan is resulted exclusively from a G-A transition at nucleotide 145 in exon 2 of the TSH beta-subunit gene. All reported cases were from the inbred in Shikoku Island. We describe here a 10-year-old boy with hereditary TSH deficiency in the same area. The patient was born with a weight of 3,225 g to non-consanguineous parents. Evaluation at age 2 months revealed typical manifestations of cretinism without goiter. Serum T4, T3, and TSH values were 2.53 micrograms/dl, 107 ng/dl, and 0.5 microU/ml, respectively. A TRH stimulation test showed no increment of serum TSH value. Other anterior pituitary hormone levels were all within the normal range. Two oligonucleotide primers T1a and T1b were synthesized according to the sequence data. Amplified 169 bp nucleotides in exon 2 of the TSH beta gene with this primer set were digested with MaeI. Both the phenotypically normal brother and normal controls showed only the 169 bp fragment, whereas the proband showed 140 and 29 bp fragments and both parents showed three fragments; 169, 140, and 29 bp. These results were consistent with the point mutation of TSH beta gene in Japanese patients with congenital isolated TSH deficiency. Our PCR method with MaeI digestion contributes to the rapid detection of the homozygous patient and the heterozygous carrier.     

FOXA2 gene mutation in a patient with congenital complex pituitary hormone deficiency

We report a patient with congenital complex pituitary hormone deficiency (CPHD) with intestinal malrotation and anal atresia. We identified a de novo heterozygous mutation, c.664T > G (p.Cys222Gly), in the FOXA2 gene in this individual. This missense mutation had the potential to affect the DNA binding properties of the FOXA2 protein based on a protein structure prediction. Since a CPHD patient with another missense mutation and one other case with an entire gene deletion have also been reported, we speculated that a haploinsufficiency of the FOXA2 gene might be a genetic etiology for this disorder. Phenotypic similarities and differences among these three cases are also discussed.     

Increased prevalence of luteinizing hormone beta-subunit variant in Japanese infertility patients

To determine the frequency of a common luteinizing hormone variant in a Japanese population and to evaluate its significance in infertility, serum samples were collected from 169 healthy non-pregnant Japanese women, 105 healthy adult Japanese men and 97 female Japanese infertility patients. The luteinizing hormone variant includes two point mutations in the beta-subunit gene (Trp8 to Arg8 and Ile15 to Thr15). DNA from blood cells was studied in 10 healthy women, 10 men and five patients using polymerase chain reaction and direct sequencing. In immunoassays, results with a monoclonal antibody recognizing only the wild-type hormone and a polyclonal antibody recognizing the variant as well were compared as a ratio; ratios in heterozygotes and in individuals with only wild-type alleles ranged from 0.19 to 0.50 and from 0.56 to 1.21, respectively, and 0.50 was considered a 'cut-off' value for identifying individuals with the variant. For the larger subject groups, the frequency of the variant was 9.5% in normals. The mean ratio (0.80 +/- 0.35) in infertility patients was significantly lower (P < 0.01) than in healthy women (1.09 +/- 0.56), and the variant occurred more frequently in infertility patients (16.5%) than in healthy women (8.3%; P < 0.05). The variant was more frequent in patients with ovulatory disorders (43.8%) than other patients (16.0%; P < 0.05).      

The growth hormone receptor gene mutation of a japanese patient with laron syndrome

Summary Deletions and point mutations of the growth hormone (GH) receptor gene (GHR) have been identified in patients with Laron syndrome. We report the first detection of theGHR mutation among Japanese patients with Laron syndrome. Using the Japanese female patient’s genomic DNA as a template, all exons and flanking portions of introns ofGHR were amplified by polymerase chain reaction (PCR). Sequencing of the PCR products showed that the patient was homozygous for a G to A substitution at the first position of intron 4. This substitution was same as that detected in a Spanish patient and a north European patient. The base change occurred at the 5′ splice consensus sequence of intron 4, resulting in the abolition of aBanI restriction site. Since this substitution was not detected by aBanI restriction analysis in 85 control individuals, it is more likely a disease-related splice mutation than a polymorphism. The mutation in our patient was predicted to destroy the original 5′ splice site of intron 4 ofGHR and to produce a new cryptic splice site, leading to abnormal mRNA processing and a lack of GH binding activity of GH-binding protein (GHBP).     

A nonsense mutation of the human luteinizing hormone receptor gene in Leydig cell hypoplasia

Leydig cell hypoplasia (LCH) is a form of male pseudohermaphroditismin which Leydig cell differentiation and testosterone productionare impaired. This report describes the first case of a nonsensemutation (A1635C) in exon 11 of the human luteinizing hormonereceptor (hLHR) gene in two sisters with LCH. This mutationcauses loss of function of the receptor by introducing a stopcodon at residue 545 in transmembrane helix 5 of the hLHR. Surfaceexpression of the truncated hLHR (hLHR-t545) in human embryonickidney cells stably transfected with cDNA encoding hLHR-t545was diminished compared to the wild-type hLHR and hCG-inducedcAMP accumulation was impaired. These results establish thatsingle base mutations in exon 11 of the hLHR gene can produceinactivation as well as activation of the hLHR. Furthermore,they demonstrate that functional domains between transmembranehelix 5 and the C-terminal cytoplasmic tail of the hLHR arerequired for normal cell surface expression of the receptorand signal transduction.     

一例Apert综合征患者的FGFR2基因突变分析

目的 确定1例Apert综合征患者是否存在成纤维细胞生长因子受体2(fibroblast growth factor receptor 2,FGFR2)基因突变.方法 收集患者及其父母的外周血,提取基因组DNA.采用PCR扩增FGFR2基因第7和第9外显子,对PCR产物进行双向测序检测基因突变.结果 发现患者FGFR2基因第7外显子的934 C→G突变,导致了FGFR2蛋白第252位丝氨酸被色氨酸取代(S252W),与国外报道的致病性突变一致.结论 FGFR2基因第7外显子的P34 C→G突变是该例Apert综合征的致病原因.     

Plasma luteinizing hormone bioactivity and immunoactivity in ovariectomized rats treated with a long-acting agonist of luteinizing hormone releasing hormone.

The dose response of a luteinizing hormone releasing hormone (LHRH) agonist in rats with high endogenous gonadotrophin levels was determined. Female rats were ovariectomized and injected with 0.3 microgram (group B), 3.2 micrograms (group C), 32 micrograms (group D) and 320 micrograms (group E) of a slow-releasing microcapsule preparation of the LHRH agonist D-Trp 6-LHRH. Control ovariectomized rats (group A) remained untreated. Plasma luteinizing hormone (LH) concentrations were measured by radioimmunoassay (RIA) before the LHRH agonist injection as well as 5, 15 and 30 days thereafter. Furthermore, LH bioactivity was determined by an in vitro rat LH bioassay in order to evaluate changes in bioactivity after administration of LHRH agonist. In control rats, plasma LH concentrations increased to 4.8 +/- 1.3 ng/ml on day 5, reaching peak levels of 9.9 +/- 1 ng/ml on day 30. In contrast to the control group, those rats which received 320 micrograms of LHRH agonist did not show any increase. Rats which received intermediate doses (groups C and D) tended to maintain levels of LH halfway between group A and group E during the first 15 days of treatment. Thereafter LH concentrations were similar to the untreated control group. The course of the LH concentrations during treatment measured by bioassay (BA) showed a similar pattern to the LH concentrations measured by RIA. The BA/RIA ratio was similar in all groups.     

局灶性真皮发育不全患者PORCN基因突变研究

目的 检测局灶性真皮发育不全(focal dermal hypoplasia,FDH)患者PORCN基因突变情况,探讨基因型与表型的相关性.方法 收集1例局灶性真皮发育不全患者及其家系3名正常成员及50名无血缘关系的健康对照者的外周血,采用PCR扩增PORCN基因所有外显子及其邻近的剪切位点进行直接测序.结果 患者PORCN基因核苷酸序列第2外显子上第149位碱基由G变为C,导致第38位氨基酸丙氨酸被脯氨酸代替(A38P),该患者家属及健康对照无此突变.患者临床表现中度.结论 该患者存在PORCN基因A38P突变,为一新的错义突变,可能是导致FDH发病机制之一.G149C基因型与中度的表型之间的关系与A38P错义突变对蛋白的影响有关,与以往结论不同.     

A pathogenic peripherin gene mutation in a patient with amyotrophic lateral sclerosis

Peripherin is a neuronal intermediate filament protein that is expressed chiefly in motor neurons and other nerve cells that project into the peripheral nervous system. Transgenic mice that over-express peripherin develop motor neuron degeneration, suggesting that mutations in peripherin could contribute to the development of motor neuron disease. In this paper, we report the identification of a homozygous mutation in the peripherin gene (PRPH) in a patient with amyotrophic lateral sclerosis (ALS). The mutation resulted in a substitution of aspartate with tyrosine at amino acid position 141, which is located within the first linker region of the rod domain. Immunocytochemical analysis of the spinal cord of the patient upon autopsy revealed distinctive large aggregates within the cell bodies of residual spinal motor neurons that contained peripherin and was also immunoreactive with antibodies to the neurofilament proteins. In order to study the effect of the mutation on peripherin assembly, we performed transient transfections. Unlike wild-type peripherin, which self-assembles to form a filamentous network, the mutant peripherin was prone to form aggregates in transfected cells, indicating that the mutation adversely affects peripherin assembly. Moreover, the neurofilament light (NF-L) protein was not able to rescue the mutant protein from forming aggregates. These data imply that mutation of PRPH is a contributing factor for ALS.     

A novel mitochondrial DNA mutation and a mutation in the Notch3 gene in a patient with myopathy and CADASIL

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is characterized by cerebral symptoms, but peripheral nerve or muscle involvement has not been reported. We describe a patient who had a stereotypic clinical presentation of CADASIL and, in addition, myopathy with ragged-red fibers, suggesting a mitochondrial disorder. Therefore we determined the nucleotide sequence in the entire coding region of the patient's mtDNA by conformation-sensitive gel electrophoresis and sequencing. Sequence of the exon 4 in the Notch3 gene was determined in a similar fashion. We found that the patient had myopathy with ragged-red fibers, and ultrastructural examination revealed mitochondrial aberrations. CADASIL was due to an R133C mutation in Notch3; in addition, we found a novel mutation 5650G>A in the tRNAAla gene in mtDNA. The mutation was heteroplasmic, with the proportions of the mutant genome being 99% in muscle, 96% in the buccal epithelium, 95% in the skin, and 65% in the blood. The absence of the mutation in a maternal cousin four times removed indicated that it was new in the pedigree. We suggest that the mtDNA mutation is pathogenic, as it was associated with a relevant clinical phenotype, it was not found among controls, and it altered a structurally important segment in the amino acid acceptor stem in the tRNAAla. Furthermore, its absence in nine patients from five families with R133C suggests that its relationship with the Notch3 mutation is coincidental.     

粘多糖贮积症Ⅰ型IDUA基因的一个新突变

目的研究粘多糖贮积症Ⅰ型（mucopolysaccharidosis type Ⅰ，MPS Ⅰ）患者发病的分子遗传学机理。方法采用聚合酶链产物直接测序的方法对患者的α-L-艾杜糖醛酸酶（alpha-L-iduronidase，IDUA）基因（仍删）外显子进行突变检测，并对发现的突变进行限制性酶切和等位基因特异性寡核苷酸杂交分析验证；同时，采集50名健康体检者血样，针对新发现的突变位点进行测序分析，以排除多态性位点的可能性。结果患者／DUA基因第2外显子和第6外显子分别出现杂合突变Q60X（178C〉T）和D203N（607G〉A），前者为已报道的无义突变，后者为新发现的错义突变。限制性酶切分析证实患者母亲是Q60X突变携带者，等位基因特异性寡核苷酸杂交分析证实患者父亲是D203N突变携带者。另外，在对50名正常人的测序分析中，未检测到D203N突变。结论筛查所得的两个点突变可能是患者的致病原因。     

A novel mutation in LICAM gene in a Japanese patient with x-linked hydrocephalus

Summary L1CAM is a member of the immunoglobulin gene superfamily of neural adhesion molecule. Abnormality of the L1CAM gene is associated with X-linked recessive form of congenital hydrocephalus (HSAS; hydrocephalus due to congenital stenosis of aqueduct of Sylvius) and some allelic disorders. Four new patients with congenital hydrocephalus consistent with the X-linked type were described. One of them had a novel mutation in the L1CAM gene.     

Juvenile hemochromatosis and hepatocellular carcinoma in a patient with a novel mutation in the HJV gene

Juvenile hemochromatosis is a rare but the most severe form of hereditary hemochromatosis which develops due to mutations in the HJV or HAMP genes. It presents in the early adulthood mainly as cardiomyopathy, hypogonadism and liver fibrosis. Unlike hereditary hemochromatosis due to HFE mutation, hepatocellular carcinoma is not known to be associated with juvenile hemochromatosis. Here, we report a patient of Arab ancestry who presented with severe cardiomyopathy. Sequence analysis of the HJV gene followed by homozygosity mapping, identified a previously undescribed homozygous missense variation in exon 3 (c.497A > G; p.H166R) in both the proband and his clinically asymptomatic brother. The former, later developed hepatocellular carcinoma. To the best of our knowledge, neither the mutation identified in our patient, nor a case of juvenile hemochromatosis with hepatocellular carcinoma has been reported before.