Functional pri-miR-34b/c rs4938723 and KRAS 3'UTR rs61764370 SNPs: Novel phenotype modifiers in Li-Fraumeni Syndrome?

PURPOSE: Li-Fraumeni Syndrome (LFS) is a rare cancer predisposing condition caused by germline pathogenic TP53 variants, in which core tumors comprise sarcomas, breast, brain and adrenocortical neoplasms. Clinical manifestations are highly variable in carriers of the Brazilian germline founder variant TP53 p.R337H, possibly due to the influence of modifier genes such as miRNA genes involved in the regulation of the p53 pathway. Herein, we investigated the potential phenotypic effects of two miRNA-related functional SNPs, pri-miR-34b/c rs4938723 and 3'UTR KRAS rs61764370, in a cohort of 273 LFS patients from Southern and Southeastern Brazil. METHODS: The genotyping of selected SNPs was performed by TaqMan® allelic discrimination and subsequently custom TaqMan® genotyping results were confirmed by Sanger sequencing in all SNP-positive LFS patients. RESULTS: Although the KRAS SNP showed no effect as a phenotype modulator, the rs4938723 CC genotype was significantly associated with development of LFS non-core tumors (first tumor diagnosis) in p.R337H carriers (p = 0.039). Non-core tumors were also more frequently diagnosed in carriers of germline TP53 DNA binding domain variants harboring the rs4938723 C variant allele. Previous studies described pri-miR-34b/c rs4938723 C as a risk allele for sporadic occurrence of thyroid and prostate cancers (non-core tumors of the LFS spectrum). CONCLUSION: With this study, we presented additional evidence about the importance of analyzing miRNA genes that could indirectly regulate p53 expression, and, therefore, may modulate the LFS phenotype, such as those of the miR-34 family.

Methylation of BDNF and SLC6A4 Gene Promoters in Brazilian Patients With Temporal Lobe Epilepsy Presenting or Not Psychiatric Comorbidities.

The relationship between epilepsy and psychiatric comorbidities has been recognized for centuries, but its pathophysiological mechanisms are still misunderstood. It is biologically plausible that genetic or epigenetic variations in genes that codify important neurotransmitters involved in epilepsy as well as in psychiatric disorders may influence the development of the latter in patients with epilepsy. However, this possibility remains poorly investigated. The aim of this study was to evaluate the methylation profile of the BDNF and SLC6A4, two genes importantly involved in neuroplasticity, in patients with temporal lobe epilepsy (TLE) regarding the development or not of psychiatric comorbidities. One hundred and thirty-nine patients with TLE, 90 females and 45 males, were included in the study. The mean age of patients was 44.0 (+12.0) years, and mean duration of epilepsy was 25.7 (+13.3) years. The Structured Clinical Interview for DSM-IV shows that 83 patients (59.7%) had neuropsychiatric disorders and 56 (40.3%) showed no psychiatric comorbidity. Mood disorders were the most common psychiatric disorder observed, being present in 64 (46.0%) of all 139 patients. Thirty-three (23.7%) patients showed anxiety disorders, 10 (7.2%) patients showed history of psychosis and 8 (5.8%) patients showed history of alcohol//drug abuse. Considering all 139 patients, 18 (12.9%) demonstrated methylation of the promoter region of both BDNF and SLC6A4 genes. A significant decreased methylation profile was observed only in TLE patients with mood disorders when compared with TLE patients without a history of mood disorders (O.R. = 3.45; 95% C.I. = 1.08-11.11; p = 0.04). A sub-analysis showed that TLE patients with major depressive disorder mostly account for this result (O.R. = 7.20; 95% C.I. = 1.01-56.16; p = 0.042). A logistic regression analysis showed that the independent factors associated with a history of depression in our TLE patients was female sex (O.R. = 2.30; 95% C.I. = 1.02-5.18; p = 0.044), not controlled seizures (O.R. = 2.51; 95% C.I. = 1.16-5.41; p = 0.019) and decreased methylation in BDNF and SLC6A4 genes (O.R. = 5.32; 95% C.I. = 1.14-25.00; p = 0.033). Our results suggest that BDNF or SLC6A4 genes profile methylation is independently associated with depressive disorders in patients with epilepsy. Further studies are necessary to clarify these matters.

MIR605 rs2043556 is associated with the occurrence of multiple primary tumors in TP53 p.(Arg337His) mutation carriers.

Li-Fraumeni and Li-Fraumeni-like (LFS/LFL) Syndrome are cancer predisposition syndromes caused by germline pathogenic variants in TP53 and are associated with an increased risk of multiple early-onset cancers. In Southern and Southeastern Brazil, a germline founder variant with partial penetrance located in the oligomerization domain of TP53, c.1010G>A p.(Arg337His, commonly known as R337H), has been detected in 0.3% of the general population. Recently, the functional MIR605 variant rs2043556 (A>G) has been identified as a novel LFS phenotype modifier in families with germline TP53 DNA binding variants. In this study, our goal was to verify MIR605 rs2043556 allele frequencies and further explore its possible effects on the phenotype of 238 Brazilian individuals carrying TP53 p.(Arg337His). The MIR605 rs2043556 G allele was detected in 136 (57.1%) individuals, including 25 homozygotes (10.5%), and although it had been previously associated with an earlier mean age of tumor onset, this effect was not observed in this study (p = 0.8). However, in p.(Arg337His) mutation carriers, the GG genotype was significantly associated with the occurrence of multiple primary tumors (p = 0.005). We provide further evidence of MIR605 rs2043556 G allele's effect as a phenotype modulator in carriers of germline TP53 pathogenic variants.

Molecular analysis of TSC1 and TSC2 genes and phenotypic correlations in Brazilian families with tuberous sclerosis.

Tuberous sclerosis complex (TSC) is an autosomal dominant multisystem disorder characterized by the development of multiple hamartomas in many organs and tissues. It occurs due to inactivating mutations in either of the two genes, TSC1 and TSC2, following a second hit in a tumor suppressor gene in most hamartomas. Comprehensive screening for mutations in both the TSC1 and TSC2 loci has been performed in several cohorts of patients and a broad spectrum of pathogenic mutations have been described. In Brazil, there is no data regarding incidence and prevalence of tuberous sclerosis and mutations in TSC1 and TSC2. We analyzed both genes in 53 patients with high suspicion of tuberous sclerosis using multiplex-ligation dependent probe amplification and a customized next generation sequencing panel. Confirmation of all variants was done by the Sanger method. We identified 50 distinct variants in 47 (89%) of the patients. Five were large rearrangements and 45 were point mutations. The symptoms presented by our series of patients were not different between male and female individuals, except for the more common occurrence of shagreen patch in women (p = 0.028). In our series, consistent with other studies, TSC2 mutations were associated with a more severe phenotypic spectrum than TSC1 mutations. This is the first study that sought to characterize the molecular spectrum of Brazilian individuals with tuberous sclerosis.

Body composition in patients with classical homocystinuria: body mass relates to homocysteine and choline metabolism.

INTRODUCTION: Classical homocystinuria is a rare genetic disease caused by cystathionine ß-synthase deficiency, resulting in homocysteine accumulation. Growing evidence suggests that reduced fat mass in patients with classical homocystinuria may be associated with alterations in choline and homocysteine pathways. This study aimed to evaluate the body composition of patients with classical homocystinuria, identifying changes in body fat percentage and correlating findings with biochemical markers of homocysteine and choline pathways, lipoprotein levels and bone mineral density (BMD) T-scores. METHODS: Nine patients with classical homocystinuria were included in the study. Levels of homocysteine, methionine, cysteine, choline, betaine, dimethylglycine and ethanolamine were determined. Body composition was assessed by bioelectrical impedance analysis (BIA) in patients and in 18 controls. Data on the last BMD measurement and lipoprotein profile were obtained from medical records. RESULTS: Of 9 patients, 4 (44%) had a low body fat percentage, but no statistically significant differences were found between patients and controls. Homocysteine and methionine levels were negatively correlated with body mass index (BMI), while cysteine showed a positive correlation with BMI (p<0.05). There was a trend between total choline levels and body fat percentage (r=0.439, p=0.07). HDL cholesterol correlated with choline and ethanolamine levels (r=0.757, p=0.049; r=0.847, p=0.016, respectively), and total cholesterol also correlated with choline levels (r=0.775, p=0.041). There was no association between BMD T-scores and body composition. CONCLUSIONS: These results suggest that reduced fat mass is common in patients with classical homocystinuria, and that alterations in homocysteine and choline pathways affect body mass and lipid metabolism.

Tryptophan hydroxylase 2 (TPH2) gene polymorphisms and psychiatric comorbidities in temporal lobe epilepsy.

Psychiatric comorbidities are frequent in temporal lobe epilepsy (TLE). It is plausible that variance in serotonin-related genes is involved in the susceptibility of these associations. We report here the results on the association of tryptophan hydroxylase 2 (TPH2) gene polymorphisms with psychiatric comorbidities in TLE. A cohort study was conducted on 163 patients with TLE. We assessed the influence of the rs4570625 and rs17110747 polymorphisms in the TPH2 gene on psychiatric comorbidities in TLE. In patients with TLE, the presence of the T allele in the rs4570625 polymorphism was associated with psychotic disorders (OR=6.28; 95% CI=1.27-17.54; p=0.02), while the presence of the A allele in the rs17110747 polymorphism was associated with alcohol abuse (OR=20.33; 95% CI=1.60-258.46; p=0.02). Moreover, we identified male gender (OR=11.24; 95% CI=1.68-76.92; p=0.01) and family history of psychiatric disorder (OR=15.87; 95% CI=2.46-100; p=0.004) as factors also associated with alcohol abuse in TLE. Conversely, a family history of epilepsy was inversely associated with alcohol abuse (OR=0.03; 95% CI=0.001-0.60; p=0.02). Tryptophan hydroxylase 2 gene allele variants might be risk factors for psychiatric conditions in TLE. More specifically, we observed that the T allele in the rs4570625 polymorphism was associated with psychotic disorders, and the A allele in the rs17110747 TPH2 polymorphism was associated with alcohol abuse in patients with TLE. We believe that this study may open new research venues on the influence of the serotonergic system associated with psychiatric comorbidities in epilepsy.

Prevalence of 185delAG and 5382insC mutations in BRCA1, and 6174delT in BRCA2 in women of Ashkenazi Jewish origin in southern Brazil.

Certain mutations in BRCA1 and BRCA2 genes are frequent in the Ashkenazi Jewish population. Several factors contribute to this increased frequency, including consanguineous marriages and an event known as a "bottleneck", which occurred in the past and caused a drastic reduction in the genetic variability of this population. Several studies were performed over the years in an attempt to elucidate the role of BRCA1 and BRCA2 genes in susceptibility to breast cancer. The aim of this study was to estimate the carrier frequency of certain common mutations in the BRCA1 (185delAG and 5382insC) and BRCA2 (6174delT) genes in an Ashkenazi Jewish population from Porto Alegre, Brazil. Molecular analyses were done by PCR followed by RFLP (ACRS). The carrier frequencies for BRCA1 185delAG and 5382insC were 0.78 and 0 respectively, and 0.4 for the BRCA2 6174deT mutation. These findings are similar to those of some prior studies but differ from others, possibly due to excluding individuals with a personal or family history of cancer. Our sample was drawn from the community group and included individuals with or without a family or personal history of cancer. Furthermore, increased dispersion among Ashkenazi subpopulations may be the result of strong genetic drift and/or admixture. It is therefore necessary to consider the effects of local admixture on the mismatch distributions of various Jewish populations.