Mothers of children with Down syndrome: a clinical and epidemiological study.

Down syndrome is the main genetic cause of intellectual disability. Many studies describe the clinical characteristics of DS patients; however, few have investigated the clinical profile of mothers who have children with DS. Advanced maternal age (≥ 35 years old) is a risk factor for DS. Although there is an overall increase in pregnancies among women with advanced maternal age, there is still a lack of awareness of the increased risk of aneuploidy. Here, we reported the clinical and epidemiological profile of DS children and their mothers in a public reference hospital in the State of Rio de Janeiro, Brazil. For data collection, we performed a face-to-face interview guided by a structured questionnaire with closed-ended questions. A total of 344 individuals, 172 mothers and their DS children, were included in this study. Our results show that 56% of the mothers sampled were ≥ 35 years of age at childbirth. Although 98% of them received prenatal care, only 4% obtained a prenatal diagnosis of DS. Most mothers reported not drinking alcohol or smoking cigarettes during pregnancy. Furthermore, 91% of women took prenatal vitamins and supplements; however, 47% were not aware of their benefits for a healthy pregnancy. Given the strict correlation between advanced maternal age and DS, prenatal care should include genetic counseling for women over 35 years of age. This study highlights the importance of prenatal care and the urgent need for better DS screening allowing for immediate postnatal care, positively impacting the life expectancy of these patients.

Intranasal perillyl alcohol therapy improves survival of patients with recurrent glioblastoma harboring mutant variant for MTHFR rs1801133 polymorphism.

BACKGROUND: Polymorphisms in MTHFR gene influence risk and overall survival of patients with brain tumor. Global genomic DNA (gDNA) methylation profile from tumor tissues is replicated in peripheral leukocytes. This study aimed to draw a correlation between rs1801133 MTHFR variants, gDNA methylation and overall survival of patients with recurrent glioblastoma (rGBM) under perillyl alcohol (POH) treatment. METHODS: gDNA from whole blood was extracted using a commercially available kit (Axygen) and quantified by spectrophotometry. Global gDNA methylation was determined by ELISA and rs1801133 polymorphism by PCR-RFLP. Statistical analysis of gDNA methylation profile and rs1801133 variants included Mann-Whitney, Kruskal-Wallis, Spearman point-biserial correlation tests (SPSS and Graphpad Prism packages; significant results for effect size higher than 0.4). Prognostic value of gDNA methylation and rs1801133 variants considered survival profiles at 25 weeks of POH treatment, having the date of protocol adhesion as starting count and death as the final event. RESULTS: Most rGBM patients showed global gDNA hypomethylation (median = 31.7%) and a significant, moderate and negative correlation between TT genotype and gDNA hypomethylation (median = 13.35%; rho = - 0.520; p = 0.003) compared to CC variant (median = 32.10%), which was not observed for CT variant (median = 33.34%; rho = - 0.289; p = 0.06). gDNA hypermethylated phenotype (median = 131.90%) exhibited significant, moderate and negative correlations between TT genotype (median = 112.02%) and gDNA hypermethylation levels when compared to CC (median = 132.45%; rho = - 0,450; p = 0.04) or CT (median = 137.80%; rho = - 0.518; p = 0.023) variants. TT variant of rs1801133 significantly decreased gDNA methylation levels for both patient groups, when compared to CC (d values: hypomethylated = 1.189; hypermethylated = 0.979) or CT (d values: hypomethylated = 0.597; hypermethylated = 1.167) variants. Positive prognostic for rGBM patients may be assigned to gDNA hypermethylation for survivors above 25 weeks of treatment (median = 88 weeks); and TT variant of rs1801133 regardless POH treatment length. CONCLUSION: rGBM patients under POH-based therapy harboring hypermethylated phenotype and TT variant for rs1801133 had longer survival. Intranasal POH therapy mitigates detrimental effects of gDNA hypomethylation and improved survival of patients with rGBM harboring TT mutant variant for MTHFR rs1801133 polymorphism. TRIAL REGISTRATION: CONEP -9681- 25,000.009267 / 2004. Registered 12th July, 2004.

Betaine-homocysteine methyltransferase 742G>A polymorphism and risk of down syndrome offspring in a Brazilian population.

Down syndrome (DS) is the most common form of mental retardation of genetic etiology. Several polymorphisms in genes involved with the folic acid cycle have been associated to the risk of bearing a DS child; however, the results are controversial. Betaine-homocysteine methyltransferase (BHMT) is a key enzyme of folate pathway, and catalyzes the remethylation of homocysteine into methionine. Recent studies suggest that the polymorphism BHMT 742G>A may be associated with a decreased risk of having a DS child. We herein investigate the association of this polymorphism with the occurrence of DS in a Brazilian population. We have genotyped 94 mothers of DS infants (DSM) and 134 control mothers (CM) for this polymorphism through PCR-RFLP, and found significant differences for both BHMT 742G>A genotype (P=0.04) and allele (P=0.03) frequencies between DSM and CM. The observed genotypic frequencies were GG=0.45; GA=0.45 and AA=0.10 in CM, and GG=0.54; GA=0.38 and AA=0.02 in DSM. Allelic frequencies were G=0.68 and A=0.32 in CM and G=0.78 and A=0.22 in DSM. The presence of the mutant BHMT 742 A allele decreases 40% the risk of bearing a DS child (OR=0.61; 95% CI: 0.40-0.93; P=0.03), and the risk is diminished up to >80% in association with the homozygous genotype (OR=0.17; 95% CI: 0.04-0.80; P=0.01). Our results indicate that women harboring the single nucleotide polymorphism BHMT 742G>A have a decreased risk of a DS pregnancy, and further studies are necessary to confirm this protective effect.

MTRR 66A>G polymorphism as maternal risk factor for Down syndrome: a meta-analysis.

Down syndrome (DS) is the most common cause of mental retardation. Recent reports have investigated possible genetic factors that may increase maternal risk for DS. Methionine synthase reductase (5-methyltetrahydrofolate-homocysteine methyltransferase reductase MTRR) plays an important role in folic acid pathway and a common polymorphism (c.66A>G) has been associated with DS but results were controversial. This meta-analysis summarizes the available data concerning this association. Online major databases were searched to identify case-control studies regarding MTRR 66A>G polymorphism and DS. Crude odds ratios (OR) and 95% confidence intervals (CI) were calculated for maternal risk to have a DS child both using fixed and random effects (RE) models. Eleven articles from six populations were identified, including 1226 DS mothers and 1533 control mothers. Heterogeneity among studies was significant (Q=29.7, DF=10, p=0.001; I(2)=66.3%). The pooled OR in a RE model showed an increase in the risk of having a DS child associated with the G allele (OR 1.23, 95% CI 1.02-1.49). The fixed effect pooled OR was 1.19 (95% CI 1.08-1.31). This meta-analysis indicates that maternal MTRR 66A>G polymorphism is associated with an increased risk of having a DS child.

Detection of mutations in GATA1 gene using automated denaturing high-performance liquid chromatography and direct sequencing in children with Down syndrome.

Denaturing high-performance liquid chromatography (dHPLC) was developed to screen DNA variations by separating heteroduplex and homoduplex DNA fragments by ion-pair reverse-phase liquid chromatography. In this study, we have evaluated the dHPLC screening method and direct sequencing for the detection of GATA1 mutations in peripheral blood and bone marrow aspirates samples from children with Down syndrome (DS). Cases were ascertained consecutively as part of an epidemiological study of DS and hematological disorders in Brazil. A total of 130 samples corresponding to 115 children with DS were analysed using dHPLC and direct sequencing methods to detect mutations in GATA1 exons 2, 3 and 4 gene sequences. The overall detection rate of sequencing and dHPLC screening methods was similar. Twenty mutations were detected in exon 2 and one mutation in exon 3 (c.231_232 dupGT) sequences of acute megakaryoblastic leukemia and transient leukemia samples. Four GATA1 mutations were newly described [c.155C > G; c.156_178 del23 bp; c.29_30 del GG; c.182C > A and c.151A > T,c.153_162 del 10 bp). Out of four, three had single nucleotide change. In conclusion, our results indicate that dHPLC is an efficient and valuable tool for GATA1 mutational analysis.

MTHFR 677C-->T and 1298A-->C polymorphisms in children with Down syndrome and acute myeloid leukemia in Brazil.

Down syndrome (DS) is an important risk factor associated with acute leukemia (AL). The presence of polymorphisms that reduce 5,10-methylenetetrahydrofolate reductase (MTHFR) activity has been linked to the multifactorial leukemogenic process. The authors have conducted a study to test whether 677C-->T and/or 1298A-->C polymorphisms of MTHFR would play an additional role in susceptibility of acute myeloid leukemia (AML) in DS children. They also verified whether any polymorphism in the MTHFR gene was associated with the risk of DS. Genetic polymorphisms determination was carried out in 248 samples from healthy individuals as controls and a total of 115 DS children (65 without leukemia and 50 with AML). The present study failed to reveal any association between these polymorphisms and risk of AML in DS children. The data also indicate that MTHFR polymorphisms are not associated with risk of being a DS child.

No association of the polyhistidine tract polymorphism of the ZIC2 gene with neural tube defects in a South American (ECLAMC) population.

The ZIC genes comprise a family of transcriptional factors associated with neural tube defects (NTDs) in mice and with holoprosencephaly in humans. An allelic variant of ZIC2, a CAC repeat within the first exon, was reported in association with an increased risk of non-syndromic NTDs in patients with a Hispanic ethnic background. We investigated whether this 10-residue histidine tract polymorphism of the ZIC2 gene (c.718_720dupCAC) was associated with the risk of NTDs in a sample of 138 patients and their parents from the Latin American Collaborative Study of Congenital Malformations (ECLAMC) hospital network. Analysis with log-linear models of 138 family triads of mother, father and affected child did not provide evidence to support the notion that case (or maternal) 10H/10H or -/10H genotypes were associated with NTDs in this South American population sample, where the 10H variant occurred in 5% of newborns affected with NTDs. We also described the first example of the homozygous state of the 10H allele in a patient with cephalocele, holoprosencephaly and microphthalmia, but did not ascertain whether this polymorphism is associated with the increased risk of a specific subgroup of NTDs, as a normal father of a patient with anencephaly presented the same genotype.

Non-Latin European descent could be a requirement for association of NTDs and MTHFR variant 677C > T: a meta-analysis.

There are several studies that have found a positive association between neural tube defects (NTDs) and the common mutation 677C > T of 5,10-methylenetetrahydrofolate reductase (MTHFR), and others that have not found such an association. We updated the meta-analyses of the published data about NTDs and MTHFR 677C > T variant from January 1994 to October 2005 identifying 170 potentially relevant studies. After applying pertinent exclusion criteria, 37 different populations from 32 studies were included in the meta-analysis, with a total of 3,530 cases and 6,296 controls. Further we stratified the data according to geographical region and ethnicity, and produced two separated meta-analyses for non-Latin European and Latin European descent populations. The general (odds ratio 1.41; 95% confidence interval 1.24-1.59), and the non-Latin European meta-analyses (1.62; 1.38-1.90) indicate an association of TT genotype and NTDs; no association was demonstrated for Latin European populations (1.16; 0.95-1.43). The examination of non-Latin European studies revealed that the association of TT genotype with NTD has only been proven for Irish populations, both by case-control studies, and by family-based tests, such as the allele transmission disequilibrium test (TDT).

Is there a familial link between Down's syndrome and neural tube defects? Population and familial survey.

OBJECTIVE: To verify whether Down's syndrome and neural tube defects arise more often in the same family than expected by chance. DESIGN: Population and familial survey. SETTING: Network of maternity hospitals in the Latin American collaborative study of congenital malformations (ECLAMC) in Argentina, Bolivia, Brazil, Chile, Colombia, Ecuador, Paraguay, Peru, Uruguay, and Venezuela between 1982 and 2000. PROBANDS: 2421 cases of neural tube defects, 952 of hydrocephalus, and 3095 of Down's syndrome registered from a total of 1 583 838 live births and stillbirths. MAIN OUTCOME MEASURES: Observed number of cases of Down's syndrome among siblings of probands with a neural tube defect or hydrocephalus and number expected on the basis of maternal age; observed number of cases of neural tube defects or hydrocephalus among siblings of probands with Down's syndrome and number expected according to the prevalence in the same population. RESULTS: Five cases of Down's syndrome occurred among 5404 pregnancies previous to a case of neural tube defect or hydrocephalus, compared with 5.13 expected after adjustment by maternal age. Twelve cases of neural tube defect or hydrocephalus occurred among 8066 pregnancies previous to a case of Down's syndrome, compared with 17.18 expected on the basis of the birth prevalence for neural tube defects plus hydrocephalus in the same population. CONCLUSION: No association occurred between families at risk of neural tube defects and those at risk of Down's syndrome.