Oocyte maturation arrest produced by TUBB8 mutations: impact of genetic disorders in infertility treatment

Oocyte maturation defect is a challenging situation in the management of infertility, the etiology may be related to endocrine causes, protocols used in ovarian stimulation, oocyte intrinsic defects or procedures in embryology laboratory. We report three Mexican females in treatment for primary infertility with non-mature oocytes after ovary stimulation and oocyte capture in whom a genetic diagnosis of TUBB8-oocyte maturation defect was revealed by exome sequencing. Two couples achieved pregnancies though oocyte donation after establishing the genetic etiology. Our results expand the role of TUBB8-disorders in patients of non-Asian ethnicity. Oocyte maturation defects of monogenic origin are a growing group of disorders that endocrinologists and reproductive medicine specialists should be aware in order to provide referral to genetics for establish a correct and opportune diagnosis.

Y chromosome microdeletions in Mexican males of couples with idiopathic recurrent pregnancy loss

AIM

To analyze the presence of Y chromosome microdeletions in males of Mexican couples with idiopathic recurrent pregnancy losses (RPL).

METHODS

Seventy-one males from couples with RPL and 66 fertile males as controls were studied. DNA was isolated from peripheral lymphocytes and used to run multiplex polymerase chain reactions. Regions AZFa (sY84, sY86), AZFb (sY127, sY134) and AZFc (sY254, sY255) of the Y chromosome were analyzed according to valid guidelines recommended by the European Academy of Andrology and the European Molecular Genetics Quality Network. Also, the sequence tagged sites (STSs): DYS262 (sY67), DYS220 (sY129), DYF85S1 (sY150), DYF86S1 (sY152) and DYF87S1 (sY153) were included in order to analyze STSs previously reported as deleted. A power analysis to support our simple size was performed.

RESULTS

Results show an absence of Y chromosome microdeletions in males of couples with RPL and controls with an acceptable statistical power.

CONCLUSION

The study did not show an association of recurrent pregnancy loss and Y chromosome microdeletions in Mexican male partners. Based on the results, the study of Y chromosome microdeletions in couples with RPL is not considered clinically relevant.

[The effect of MTHFR polymorphisms, pregnancy and first intercourse on cervical cancer in a population from the Northeastern Mexico]

OBJECTIVE

To investigate the possible association among MTHFR polymorfhisms, environmental factors and cervical cancer (CC) in the Mexican population.

METHODS

Seventy patients with CC and 89 control women were questioned about clinical data and their 677 and 1298 genotypes of MTHFR gene were analized.

RESULTS

Multipregnancies (0-2 vs. > or = 3, OR 2.1), an early age of first intercourse (IVS) (17 < or = vs. > or = 18 years, OR 4.3) or both factors (OR 3.5) were significantly associated with CC. MTHFR 677, 1298 polymorphisms and their combinations were not different between cases and controls. However, a significant association between pregnancies, IVS and MTHFR polymorphisms (presence of 1298C allele or 677TT genotype) was observed. The 1298C allele plus multipregnancies and IVS < or = 17 years, or both factors, increased 4.3, 5.3, and 11.8 times the risk for CC, respectively, while 677TT genotype changed the risk 2.0, 1.9, and 4.2 times, respectively.

CONCLUSION

The 1298C allele increases the risk of CC strongly in women with multipregnancies and early age of IVS, while 677TT genotype has a lower risk without becoming a protection factor.

[677T mutation of the MTHFR gene in adenomas and colorectal cancer in a population sample from the Northeastern Mexico. Preliminary results]

INTRODUCTION

Adequate intake of folates has been associated to low prevalence of colon cancer. Methylenetetrahydrofolate reductase enzyme (MTHFR) plays an important role in folate metabolism. The role of the 677 mutation at the MTHFR gene in the risk for colorectal cancer remains controversial. A recent report established that this mutation has a high prevalence in the healthy Mexican population.

AIMS

To analyze the prevalence of 677T MTHFR mutation in patients with colorectal cancer and controls without chronic gastrointestinal disorders.

METHODS

Seventy-four colorectal cancer, 32 adenomas and 110 normal samples were analyzed. Patients and controls were matched for sex and age. For each sample, DNA isolation, PCR, and mutation detection by restriction enzyme digestion were performed to determine the allele at the 677 position in the MTHFR gene.

RESULTS

Genotype 677C/677C was found in 18.7, 20.3, and 30.9% in adenomas, cancer lesions and controls, respectively. Frequencies of the 677C/677T genotype were 59.4, 56.7, and 47.3%, in adenomas, cancer lesions, and controls, respectively. Genotype 677T/677T was found in 21.9, 23.0, and 21.8% in adenomas, cancer lesions, and controls, respectively. The odds ratio between genotypes carrying the mutation (T/T and C/T) and normal genotype (CC) was 1.81 (IC 95% 0.97-3.3), chi 2 = 3.5, p = 0.06.

CONCLUSION

Our results showed that persons who carry the 677T mutation at MTHFR locus have a tendency for an increased risk for colorectal cancer. This study supports the basic concept that low levels of folic acid contribute with the colorectal cancer pathogenesis. Our lack of statistic significance may be due to reduced sample size.