Ana Paula Carneiro Brandalize

Association of the HLA-G 14-bp insertion/deletion polymorphism with juvenile idiopathic arthritis and rheumatoid arthritis

We tested the possible association of the 14-bp polymorphism of the HLA-G gene in the course of two inflammatory diseases, rheumatoid arthritis (RA) and juvenile idiopathic arthritis (JIA). Patients and controls were genotyped for the 14-bp polymorphism by polymerase chain reaction with specific primers for the exon 8 of the human leukocyte antigen (HLA)-G gene and the amplified fragment was visualized in a 6% polyacrylamide gel. A total of 106 JIA patients, 265 RA patients, 356 healthy adults and 85 healthy children were genotyped for the 14-bp polymorphism. Female JIA patients presented a higher frequency of the -14 bp allele when compared with female healthy children (0.743 and 0.500, corrected P=0.003), which reflected in the JIA group as a whole. This increased frequency of the -14-bp allele was observed in all JIA subtypes. In RA patients, no differences in allelic and genotypic frequencies were observed between patients and controls. No correlations were observed among genotype and disease severity or clinical manifestations. Our data suggest that the HLA-G -14 bp allele is probably a risk factor for JIA, mainly in females. Considering the differences observed in relation to gender, we suggest that hormonal differences can interfere with the development of JIA. Considering the RA patients, our data agree with results from the literature and highlight the differences in the etiology of RA and JIA.

Evaluation of C677T and A1298C polymorphisms of the MTHFR gene as maternal risk factors for Down syndrome and congenital heart defects

Abnormal folate/homocysteine metabolism due to polymorphisms in genes involved in this pathway has been implicated as an etiologic factor in Down syndrome (DS). This case–control study aimed to evaluate the effect of maternal C677T and A1298C polymorphisms of the methylenetetrahydrofolate reductase (MTHFR) as risk factors for the development of DS and congenital heart defects (CHD). The distribution of these genotypic variants was similar between mothers of children with DS (n = 239) and control mothers of normal children (n = 197), but the combined genotypes 677CT or TT and 1298AA increased the risk of having offspring with DS (OR = 1.99; 95% CI 1.11–3.55). The presence of the 677T allele in case mothers resulted in a 2.07‐fold higher odds of CHD in the offspring (P < 0.01). Among the 57 mothers of CHD‐affected children with DS who carried the MTHFR 677CT or TT genotypes and did not have periconceptional folic acid intake, we observed a 2.26‐fold increased odds (95% CI 1.25–4.09) of having any CHD‐affected child with DS. Our results show that MTHFR genetic polymorphisms may be involved in the etiology of DS in our population when controlling for age. We noted a borderline significant association for the C677T polymorphism (P = 0.05). Maternal 677T allele may be associated with an increased occurrence of CHD in children with DS and we anticipate that women who carry this polymorphism would benefit from periconceptional folic acid supplementation.

Polymorphisms in genes MTHFR, MTR and MTRR are not risk factors for cleft lip/palate in South Brazil

Non-syndromic cleft lip and palate (CL/P) occurs due to interaction between genetic and environmental factors. Abnormalities in homocysteine metabolism may play a role in its etiology due to polymorphisms in genes involved in this pathway. Because of the involvement of MTHFR, MTR and MTRR genes with folate metabolism and the evidence that maternal use of folic acid in early pregnancy reduces the risk for CL/P, we evaluated the influence of their polymorphisms on the etiology of CL/P through a case-control study. The analyses involved 114 non-syndromic phenotypically white children with clefts (case) and 110 mothers, and 100 non-affected (control) children and their mothers. The polymorphisms 677C>T of MTHFR, 2756A>G of MTR, and 66A>G of MTRR genes were analyzed by PCR-RFLP. Allelic frequencies did not differ from other studies conducted on white populations for MTHFR 677T allele (0.35) and for MTR 2756G allele (0.17), but MTRR 66G allele frequency (0.35) was lower than observed elsewhere. The genotypic distribution of the 677C>T polymorphisms under study did not show significant differences between CL/P patients, their mothers and controls. These results suggest that the alterations of folate metabolism related to these polymorphisms are not involved in clefting in the population under study.

Maternal Gene Polymorphisms Involved in Folate Metabolism as Risk Factors for Down Syndrome Offspring in Southern Brazil

This study aimed to investigate the role of maternal polymorphisms, as well as their risk genotypes combinations of MTR A2756G, MTRR A66G, CBS 844ins68, and RFC A80G, involved in folate/homocysteine metabolism, as possible risk factors for Down syndrome (DS) in Southern Brazil. A case-control study was conducted with 239~mothers of DS children and 197 control mothers. The investigation of polymorphisms was performed by PCR and PCR-RFLP. The distribution of genotypic variants was similar in both groups when they were analyzed separately. An investigation of combined risk genotypes showed that the risk of having a DS child for one, two or three risk genotypes was 6.23, 6.96 and 5.84 (95%CI 1.48–26.26; 1.69–28.66; 1.37–24.86), respectively. The combined MTRR 66G and MTHFR 677T alleles were significantly more common among mothers of children with DS than among control mothers (OR 1.55; IC 95% 1.03–2.35). The results show that individual polymorphisms studied in this work are not associated with DS; however, the effects of the combined risk genotypes among MTR, MTRR, CBS and RFC genes are considered maternal risk factors for DS offspring in our population.

Influence of the 5-HTTLPR polymorphism and environmental risk factors in a Brazilian sample of patients with autism spectrum disorders

The 5-HTTLPR polymorphism of serotonin transporter gene is widely investigated in association studies in autism spectrum disorders (ASD). The results of such studies, however, remain controversial possibly due to the great genetic heterogeneity related to ASD and the lack of evaluation of the triallelic functional structure of 5-HTTLPR. This study tested for association between the 5-HTTLPR and ASD in a Brazilian sample by case-control and family-based association test (FBAT) methods, considering the biallelic and triallelic structures of this polymorphism. In addition, we performed an exploratory analysis of associations between specific clinical outcomes of ASD patients and 5-HTTLPR as well as several prenatal environmental factors. Genotyping was achieved in 151 ASD patients, 179 unrelated controls and 105 complete trios. There was no evidence of association between the 5-HTTLPR with ASD in both case-control and FBAT tests, but the LaLa 5-HTTLPR genotype was associated with mood instability in patients (P=0.006). The prenatal exposure to potential neuroteratogenic drugs was associated with epilepsy (P<0.001). Our findings suggest that the 5-HTTLPR is not associated with ASD in the Brazilian population, even considering the triallelic structure. Additionally, this study suggested a role of the 5-HTTLPR and environmental factors in the clinical expression of ASD.

MTHFR C677T is not a risk factor for autism spectrum disorders in South Brazil.

Many studies have suggested that autism may be associated with metabolic abnormalities in the folate/homocysteine pathway, which is involved in DNA methylation, thus altering gene expression. One of the most important polymorphisms in this pathway is C677T of the methylenetetrahydrofolate reductase gene, because the T allele is associated with a decrease in enzymatic activity. We evaluated the association between C677T polymorphism and autism spectrum disorders through a case--control study. In addition, we analyzed the influence of this polymorphism on certain autistic behaviors like complex body movements, self-injury and averted gaze according to the Autism Diagnostic Interview-Revised. The analyses involved 151 children with idiopathic autism spectrum disorder and 100 healthy control children. The frequency of the T allele was 0.38 for the case group and 0.35 for the control group (P=0.77). The genotypic distribution did not show significant differences between cases and controls (P=0.72), nor association between the T allele and selected behaviors.

Maternal SNPs in the p53 Pathway: Risk Factors for Trisomy 21?

The p53 family and its regulatory pathway play an important role as regulators of developmental processes, limiting the propagation of aneuploid cells. Its dysfunction or imbalance can lead to pathological abnormalities in humans. The aim of this study was to evaluate the effect of maternal polymorphisms TP53 c.215G>C (P72R), TP73 4 c.-30G>A and 14 c.-20C>T, MDM2 c.14+309T>G (SNP309), MDM4 c.753+572C>T and USP7 c.2719-234G>A as risk factors for Down Syndrome (DS) birth. A case-control study was conducted with 263 mothers of DS children and 196 control mothers. The distribution of these genotypic variants was similar between case and control mothers. However, the combined alleles TP53 C and MDM2 G, and TP53 C and USP7 A increased the risk of having offspring with DS (OR = 1.84 and 1.77; 95% CI; P < 0.007 and 0.018, respectively). These results suggest that, although the individual polymorphisms were not associated with DS birth, the effect of the combined genotypes among TP53, MDM2 and USP7 genes indicates a possible role of TP53 and its regulatory pathway as a risk factor for aneuploidy.

p53 signaling pathway polymorphisms, cancer risk and tumor phenotype in TP53 R337H mutation carriers

Li-Fraumeni and Li-Fraumeni-like syndrome (LFS/LFL) are clinically heterogeneous cancer predisposition syndromes characterized by diagnosis of early-onset and often multiple cancers with variable tumor patterns and incomplete penetrance. To date, the genetic modifiers described in LFS/LFL have been shown to map to either TP53 or its main negative regulator, MDM2. Additionally, all studies were focused on families with different TP53 germline mutations. Hence, in this study we explored the effect of the most studied polymorphisms of p53 pathway genes on clinical manifestations of individuals carrying the founder TP53 mutation R337H (n = 136) and controls (n = 186). Cancer-affected carriers had been diagnosed either with adrenocortical carcinoma (ACC, n = 29) or breast cancer (BC, n = 43). Allelic discrimation using TaqMan assay was used for genotyping MDM2 SNP 309 (rs2279744) as well as MDM4 (rs1563828) and USP7 (rs1529916) polymorphisms. We found significantly higher MDM2 SNP 309 GG genotype and G allele frequencies in the LFS cohort than in controls. Furthermore, median age at first diagnosis was earlier in MDM2 SNP309 GG carriers when compared to other genotypes for both cancers (ACC: age 1 vs. 2 years; BC: age 35 vs. 43 years, respectively), although not statistically different. The allelic and genotypic frequencies for all SNPs did not differ between cancer affected and unaffected carriers, neither between patients with ACC or BC. In conclusion, our results suggest that MDM2 SNP 309 may contribute to the LFL phenotype and also to an earlier age at diagnosis of ACC and BC cancer in carriers of the R337H founder mutation.