The presence of joint heterozygotic polymorphism in the codifying gene for MTHFR was a risk factor for having a child with trisomy 21.

Turner syndrome (TS) is an interesting model for investigating the association between methylenetetrahydrofolate reductase (MTHFR) gene polymorphisms and non-disjunction because of the high frequency of chromosomal mosaicism among patients with this syndrome. We determined the frequencies of MTHFR 677C ® T and 1298A ® C polymorphic mutations in 49 patients with TS and 200 control individuals. The frequency of the 677C ® T allele was 0.39 for patients and 0.29 for controls while that of the 1298A ® C allele was 0.28 for patients and 0.25 for controls. Genotype frequencies were shown to be different in patients and controls (c 2 = 12.143; p = 0.033), and this was attributable to the higher frequency of the C677C ® T /677C ® T genotype among TS patients. In homozygotes, this mutation might have an effect on somatic chromosome disjunction by decreasing MTHFR activity.

This article contains all the methods for pré-natal diagnosis of genetic and chromosomal abnormalities, as well infectious dis

The measurement of nuchal translucency was found to be fairly accurate as an ultrasound marker for fetal abnormalities and measurements equal to or higher than 2.5 mm were the best fixed cutoff points.

Fanconi anaemia (FA) is a recessive autosomal disease determined by mutations in genes of at least eleven complementation groups, with distinct distributions in different populations. As far as we know, there are no reports regarding the molecular characterisation of the disease in unselected FA patients in Brazil. Objective: This study aimed to investigate the most prevalent mutations of FANCA and FANCC genes in Brazilian patients with FA. Methods: Genomic DNA obtained from 22 racially and ethnically diverse unrelated FA patients (mean age ± SD: 14.0 ± 7.8 years; 10 male, 12 female; 14 white, 8 black) was analysed by polymerase chain reaction and restriction site assays for identification of FANCA (∆3788-3790) and FANCC (∆322G, IVS4+4A → T, W22X, L496R, R548X, Q13X, R185X, and L554P) gene mutations. Results: Mutations in FANCA and FANCC genes were identified in 6 (27.3%) and 14 (63.6%) out of 22 patients, respectively. The disease could not be attributed to the tested mutations in the two remaining patients enrolled in the study (9.1%). The registry of the two most prevalent gene abnormalities (∆3788-3790 and IVS4 + 4 → T) revealed that they were present in 18.2% and 15.9% of the FA alleles, respectively. Additional FANCC gene mutations were found in the study, with the following prevalence: ∆322G (11.4%), W22X (9.1%), Q13X (2.3%), L554P (2.3%), and R548X (2.3%) of total FA alleles. Conclusion: These results suggest that mutations of FANCA and FANCC genes are the most prevalent mutations among FA patients in Brazil.