Mutation C11994T in the mitochondrial ND4 gene is not a cause of low sperm motility in Portugal

It has recently been suggested that a hitherto unobserved mutation, C11994T, causes oligoasthenozoospermia in men from India but at the same time does not affect systems other than the motility of the sperm. There are good reasons to question this proposition, in view of the worldwide mtDNA database and the Indian record in particular. We have further analyzed the oligoasthenozoospermic samples from a previous systematic study of infertile Portuguese men and found no instance of C11994T.     

A novel heterozygous missense mutation 377T > C (V126A) of TGIF gene in a family segregated with holoprosencephaly and moyamoya disease

OBJECTIVES: To identify whether any mutations of candidate genes including SHH, ZIC2, SIX3, and TGIF exist in a Taiwanese family segregated with holoprosencephaly (HPE) and moyamoya disease. METHODS: Genotypes of the candidate genes SHH, ZIC2, SIX3, and TGIF were determined in the family members who were available for analysis by sequencing. In addition, genomic regions of another 50 unrelated Taiwanese (100 chromosomes) were studied to verify whether the nucleotide changes we found were mutations or polymorphisms. RESULTS: A novel missense mutation 377T > C and two polymorphisms (420A > G and 487C > T) in the TGIF gene were identified. No mutations in SHH, ZIC2 and SIX3 were found. The mother of the three HPE fetuses was found to be afflicted with moyamoya disease. A brief review of the mutations as well as polymorphisms reported in the TGIF gene up to 2005 is given. CONCLUSION: Molecular diagnosis can help genetic counseling in HPE, which is a heterogeneous disorder with its phenotypic and genotypic spectrum highly widened and variable. The possible association between TGIF mutation and moyamoya disease noted in our study also appeared to be novel.     

Prenatal diagnosis for a novel homozygous mutation in PKLR gene in an Indian family

OBJECTIVE: To provide prenatal diagnosis of pyruvate kinase deficiency by direct DNA analysis in an Indian family. MATERIALS AND METHOD: This case report describes diagnosis of a novel homozygous mutation in PKLR gene that subsequently helped the family in the next pregnancy. RESULTS: Advancement in molecular genetics has resulted in the prenatal diagnosis of relatively uncommon genetic disorders like pyruvate kinase deficiency. CONCLUSION: This case reiterates the importance of application of molecular genetics in clinical practice and prenatal diagnosis especially for rare, incurable genetic disorders.     

原因不明复发性流产患者血中亚甲基四氢叶酸还原酶基因C677T和A1298C位点突变的研究

目的　探讨 5 ,10 亚甲基四氢叶酸还原酶基因C6 77T和A12 98C位点突变与原因不明复发性流产 (unexplainedrecurrentspontaneousabortion ,URSA)易感因素的相关性。 方法　采用PCR-限制性片段长度多态性方法 ,检测 14 7例原因不明复发性流产患者 (URSA组 )和 82例有正常妊娠史的妇女 (对照组 )血中亚甲基四氢叶酸还原酶基因C6 77T和A12 98C位点突变。结果　 ( 1)C6 77T的 3种基因型在URSA组和对照组总体分布存在显著性差异 (P =0 0 12 ) ,其中URSA组 :基因型CC占 33 3% ,CT占 5 3 1% ,TT占 13 6 % ,对照组 :基因型CC占 5 2 4 % ,CT占 5 1 5 % ,TT占 6 1%。两组 6 77CC基因表达差异有显著性 (P =0 0 0 5 ) ,URSA组C和T等位基因分别为 4 0 1%、5 9 9% ,两组基因分布情况比较 ,差异有显著性 (P <0 0 0 5 ) ;( 2 )A12 98C的 3种基因型在URSA组和对照组中总体分布情况比较 ,差异无显著性 ,12 98AA/AC/CC基因型和A/C等位基因频率比较 ,差异无显著性 (P >0 0 0 5 ) ;( 3)C6 77T/A12 98C连锁基因分析显示 ,8种连锁基因型中 ,URSA组 6 77CC/ 12 98AA表达频率显著降低 ,而 6 77(CT TT) / 12 98CC仅在URSA组中表达。结论　URSA与亚甲基四氢叶酸还原酶基因C6 77T和A12 98C位点突变有关。     

Prenatal exclusion of Leigh syndrome due to T8993C mutation in the mitochondrial DNA

Leigh syndrome (LS) is a mitochondrial encephalopathy that is caused by a mutation either in the mitochondrial DNA (mtDNA) or in the nuclear encoded genes of the mitochondrial proteins. Prenatal diagnosis of defects in the mtDNA is usually problematic because of mtDNA heteroplasmy and tissue specificity. However, the mutations T8993 G/C in the ATP synthase subunit 6 gene of the mtDNA show a more even tissue distribution and do not appear to change significantly over time. There are only few reports of prenatal diagnosis of the T8993G mutation in Leigh disease. Here we describe the first prenatal genetic testing of T8993C in a fetus of a mother whose previous child had died of Leigh syndrome due to the T8993C mutation. Mutant load in the chorionic villus sample (CVS) as well as in amniocytes was undetectable, thus predicting a very high likelihood of an unaffected outcome, indicative of a healthy baby. The diagnosis was confirmed after birth. Gathering data on the prenatal diagnosis of mtDNA mutations is of great importance so that prenatal diagnosis of both T8993G and T8993C mutations can be offered routinely.     

A novel heterozygous missense mutation G316D of SIX3 gene in a Brazilian patient with holoprosencephaly-like phenotype and Langerhans cell histiocytosis

Here we report on a Brazilian female patient with the clinical manifestations of the holoprosencephaly-like phenotype who also presented with a retroocular granuloma diagnosed as Langerhans cell histiocytosis in early infancy. Mutation analysis showed a missense mutation (G316D) in the exon 2 of SIX3 gene, which was predicted as damaged by the PolyPhen program. We discuss the clinical and genetic aspects of this unusual case.     

A novel homozygous missense mutation in AK7 causes multiple morphological anomalies of the flagella and oligoasthenoteratozoospermia

Journal of Assisted Reproduction and Genetics - To identify the genetic causes of multiple morphological anomalies of the flagella (MMAF) and oligoasthenoteratozoospermia (OAT). Whole-exome...     

Lowered levels of bicarbonate in seminal plasma cause the poor sperm motility in human infertile patients

Both the adenylate cyclase activity and the motility of human sperm were stimulated by bicarbonate with the same concentration dependency. The correlation between bicarbonate levels in semen and the motility of sperm from the patients with male infertility was investigated. Bicarbonate in semen was found to originate mainly from the seminal vesicles, and a significant positive correlation was observed between bicarbonate levels and volume of semen. The motility of infertile sperm was also found to correlate positively to the seminal levels of bicarbonate. These results suggest that the lowered levels of bicarbonate in semen are at least in part responsible for the poor sperm motility in infertile patients, as a result of the failure in the activation of sperm adenylate cyclase.     

ACL(+)复发性流产与亚甲基四氢叶酸还原酶C677T和A1298C位点突变关联的研究

目的:探讨亚甲基四氢叶酸还原酶基因(methylenetetrahydrofolate reductase,MTHFR)C677T和A1298C位点突变与抗心磷脂抗体(anticard iolipin antibody,ACL)阳性复发性流产是否相关。方法:采用聚合酶链式反应-限制性片断长度多态性方法,检测39例原因不明复发性流产和82例正常对照的亚甲基四氢叶酸还原酶基因C677T和A1298C位点突变。结果:MTHFR 677 3种基因型(CC、CT和TT)在ACL(+)流产组和对照组分布有统计学差异(P=0.045),进一步分析表明,677TT在患者组中表达频率显著增大(P=0.026),T等位基因频率在患者组中也显著增大(P=0.018),MTHFR1298相关3种基因型(AA、AC和CC)和A、C等位基因频率在2组中分布无差异,同时发现8种C677T/A1298C连锁基因型,但都与ACL(+)复发性流产无关。结论:ACL(+)复发性流产与MTHFR C677T突变有关,表明除自身抗体有关的获得性凝血途径以外,遗传性凝血因素在此种类型的流产发生中也起一定的作用。     

The significance of C3435T point mutation of the MDR1 gene in endometrial cancer

The P-glycoprotein (P-gp) plays an important role in carcinogen distribution and is connected with cell differentiation and apoptotic processes leading to carcinogenesis. Interindividual differences in P-gp activity could modulate susceptibility to cancer development. The MDR1 gene, coding for P-gp, is highly polymorphic and some mutations modulate P-gp activity. Recently, association between the MDR1 C3435T polymorphism and the cancer susceptibility was shown. We have hypothesized that MDR1 polymorphism could influence endometrial cancer susceptibility. We have matched 198 women with endometrial cancer and 198 controls. An additional group of 488 healthy volunteers was investigated. The MDR1 C3435T polymorphism was tested by LightCycler assay. The distribution of MDR1 3435 genotypes was significantly different between cases and controls (P = 0.006). Genotypes containing at least one 3435T allele were statistically significant more frequent in the endometrial cancer group (86.8% vs 75.2%, OR 2.18, P = 0.004). Our observation suggests that MDR1 C3435T polymorphism is correlated with endometrial cancer susceptibility.     

A novel mutation of the fibrillin-1 gene in a newborn with severe Marfan syndrome.

Marfan syndrome in the neonatal age represents a severe early and commonly lethal manifestation of Marfan syndrome, which is caused by mutations in the gene encoding fibrillin-1 (FBN1). Here, we report a newborn with severe Marfan syndrome and a novel mutation involving cysteine substitution within one of the epidermal growth factor-like domains of FBN1.     

A De Novo novel mutation of the EDNRB gene in a Taiwanese boy with Hirschsprung disease.

Hirschsprung disease (HSCR) is a congenital disorder characterized by an absence of ganglion cells in the nerve plexuses of the lower digestive tract. Although mutations in eight different genes (EDNRB, EDN3, ECE1, SOX10, RET, GDNF, NTN, SIP1) have been identified in affected individuals, it is now clear that RET and EDNRB are the primary genes implicated in the etiology of HSCR. All eight genes are involved in the early development of the enteric nervous system, and most act through two distinct biochemical pathways mediated by RET and EDNRB. Mutations in RET and EDNRB account for up to 50% and 5% of HSCR cases in the general population, respectively. Interaction between these two signaling pathways could modify RET expression and, therefore, HSCR phenotype. Here, we report the case of a 1-year-old Taiwanese boy who presented with abdominal distension since birth and bilious vomiting after feeding. HSCR (short-segment type) was diagnosed based on X-ray, lower gastrointestinal series and biopsy findings. Mutation analysis revealed a heterozygous T>C missense mutation in exon 1 of the EDNRB gene, that substitutes the highly conserved cysteine-90 residue in the extracellular domain of the G protein-coupled receptor with an arginine residue (C90R). No RET gene mutation was detected in this patient.     

A novel androgen receptor gene mutation in a Chinese patient with complete androgen insensitivity syndrome

Objective

To identify the underlying androgen receptor gene mutation in a Chinese patient with typical symptoms of complete androgen insensitivity syndrome.

Study design

A Chinese female phenotype with 46, XY karyotype was diagnosed because of primary amenorrhea. Mutations were determined by polymerase chain reaction followed by DNA sequencing.

Results

DNA sequencing of the androgen receptor gene showed a G2439T transition causing E442X mutation in exon 1 in the patient with complete androgen insensitivity syndrome. The E442X mutation was a new de novo non-sense mutation in exon 1 of the androgen receptor gene. This non-sense mutation is located in the N-terminal transactivation domain and leads to a predicted truncated protein of 441 amino acids with loss of the end part of the N-terminal transactivation domain, and the DNA-binding and ligand-binding domain.

Conclusion

This E442X non-sense point mutation has not been described previously in cases of androgen insensitivity syndrome, and could lead to the synthesis of a short truncated non-functional androgen receptor probably responsible for the phenotype of complete androgen insensitivity syndrome in the affected individual. Gonadectomy should be planned to eliminate the risk of gonadal malignancy.     

A no-stop mutation in MAGEB4 is a possible cause of rare X-linked azoospermia and oligozoospermia in a consanguineous Turkish family

Purpose

The purpose of this study was to identify mutations that cause non-syndromic male infertility using whole exome sequencing of family cases.

Methods

We recruited a consanguineous Turkish family comprising nine siblings with male triplets; two of the triplets were infertile as well as one younger infertile brother. Whole exome sequencing (WES) performed on two azoospermic brothers identified a mutation in the melanoma antigen family B4 (MAGEB4) gene which was confirmed via Sanger sequencing and then screened for on control groups and unrelated infertile subjects. The effect of the mutation on messenger RNA (mRNA) and protein levels was tested after in vitro cell transfection. Structural features of MAGEB4 were predicted throughout the conserved MAGE domain.

Results

The novel single-base substitution (c.1041A>T) in the X-linked MAGEB4 gene was identified as a no-stop mutation. The mutation is predicted to add 24 amino acids to the C-terminus of MAGEB4. Our functional studies were unable to detect any effect either on mRNA stability, intracellular localization of the protein, or the ability to homodimerize/heterodimerize with other MAGE proteins. We thus hypothesize that these additional amino acids may affect the proper protein interactions with MAGEB4 partners.

Conclusion

The whole exome analysis of a consanguineous Turkish family revealed MAGEB4 as a possible new X-linked cause of inherited male infertility. This study provides the first clue to the physiological function of a MAGE protein.

     

The biological significance of phospholipase C beta 1 gene mutation in mouse sperm in the acrosome reaction, fertilization, and embryo development

Purpose: We carried out this study to evaluate the biological significance of phospholipase C 1 gene mutation in mouse sperm in the acrosome reaction, fertilization, and embryo development.Methods: Study subjects were divided into two groups according to the sperm [intact phospholipase C (PLC) 1 and PLC 1^–/– C57BL/6J × CBA F₁ mouse sperm] used. The positive acrosome reaction rate labeled with fluorescein isothiocyanate–Pisum sativum agglutinin, the fertilization rate, and the rate of embryos developed to the stage of morula or blastocyst in the two groups were compared.Results: The mouse sperm null for the PLC 1 gene showed a lower acrosome reaction rate than control sperm (69.2 vs 50.9%, P < 0.05). And the fertilization rate and the rate of embryos developed to the stage of morula or blastocyst were also lower in the group using PLC 1^–/– mouse sperm compared to the intact group (P < 0.05; 73.5 vs 51.8% and 15.7 vs 4.3%, respectively).Conclusions: Mutation of the PLC 1 gene in the mouse sperm reduces the acrosome reaction rate, fertilization rate, and embryo development rate, which may be the etiologic factors responsible for the low reproductive rate of PLC 1^–/– mouse.