Dento-osseous anomalies in patients with familial adenomatous polyposis: A follow-up study.

OBJECTIVE: The aim of this longitudinal study was to characterize the dento-osseous phenotype of eleven familial adenomatous polyposis (FAP) patients and twenty-two family members from four Brazilian families who were followed over nine years and to investigate adenomatous polyposis coli (APC) gene variants using a targeted next-generation sequencing approach. MATERIALS AND METHODS: Medical and dental history, oral examination, and panoramic radiography were performed to diagnose and follow up the dento-osseous anomalies. The anomalies were evaluated following the validated diagnostic tool dental panoramic radiographic score (DPRS), a system developed for high-risk FAP patients. Patients diagnosed with dento-osseous anomalies underwent cone-beam computed tomography. For genetic analysis, DNA was isolated from patients' saliva. RESULTS: Dento-osseous anomalies were identified in ten of the eleven FAP patients by panoramic radiograph evaluation. DPRS ≥ 7 (significant changes) was found in 81.8% (9/11) of FAP patients. The follow-up showed an increase in osseous jaw lesions in two young patients during adolescence. Dento-osseous anomalies were not found in non-FAP patients. A novel heterozygous nonsense pathogenic variant in APC exon 5 (c.481C > T; p.Gln161*) was identified in family 2, and a heterozygous splice-site pathogenic variant was identified in family 1 (c.532-1G > A). CONCLUSION: Our study expands the mutation spectrum of the APC gene and provides evidence that dento-osseous screening by imaging is a putative tool for early diagnosis of FAP. Also, the detection of dento-osseous anomalies in young patients with increasing osseous lesions during adolescence highlights the need for dental follow-up of high-risk FAP children. CLINICAL RELEVANCE: Dental radiographs are important for the screening and the follow-up of dento-osseous anomalies associated with FAP. It can also contribute to the early diagnosis of the disease.

Protocols for Genetic and Epigenetic Studies of Rare Diseases Affecting Dental Tissues.

This chapter describes methods related to the diagnosis of genetic dental diseases. Based on the present knowledge, clinical phenotyping and next-generation sequencing techniques are discussed. Methods necessary for Sanger sequencing, multiplex ligation-dependent probe amplification, and epigenetic modification methods are detailed. In addition, protocols for cell culture establishment and characterization from patients with inherited dental anomalies are described.

Identification of the first large deletion in the CLDN16 gene in a patient with FHHNC and late-onset of chronic kidney disease: case report.

BACKGROUND: Familial hypomagnesemia with hypercalciuria and nephrocalcinosis is a rare autosomal recessive renal disease characterized by tubular disorders at the thick ascending limb of Henle's loop. It is caused by mutations in the tight junction structural proteins claudin-16 or claudin-19, which are encoded by the CLDN16 and CLDN19 genes, respectively. Patients exhibit excessive wasting of calcium and magnesium, nephrocalcinosis, chronic kidney disease, and early progression to end-stage renal failure during infancy. CASE PRESENTATION: We here report the phenotype and molecular analysis of a female Brazilian patient with a novel large homozygous deletion in the CLDN16 gene. The proband, born from consanguineous parents, presented the first symptoms at age 20. Clinical examination revealed hypocalcemia, hypomagnesemia, nephrocalcinosis, mild myopia, high serum levels of uric acid and intact parathyroid hormone, and moderate chronic kidney disease (stage 3). She and her mother were subjected to CLDN16 and CLDN19 mutational analysis. In addition, the multiplex ligation-dependent probe amplification method was used to confirm a CLDN16 multi-exon deletion. Direct sequencing revealed a normal CLDN19 sequence and suggested a large deletion in the CLDN16 gene. Multiplex ligation-dependent probe amplification showed a homozygous CLDN16 multi-exon deletion (E2_E5del). The patient initiated conventional treatment for familial hypomagnesemia with hypercalciuria and nephrocalcinosis and progressed to end-stage kidney disease after five years. CONCLUSIONS: This study provides the first report of a large homozygous deletion in the CLDN16 gene causing familial hypomagnesemia with hypercalciuria and nephrocalcinosis with late onset of the first symptoms. This description expands the phenotypic and genotypic characterization of the disease. The late-onset chronic kidney disease in the presence of a homozygous deletion in the CLDN16 gene reinforces the great variability of genotype-phenotype manifestation in patients with familial hypomagnesemia with hypercalciuria and nephrocalcinosis.

GSTM1, GSTT1, and GSTP1 polymorphisms, breast cancer risk factors and mammographic density in women submitted to breast cancer screening.

Genetic polymorphisms in genes related to the metabolism of xenobiotics, such as genes of the glutathione S-transferases (GSTM1, GSTT1, and GSTP1) superfamily have been associated with an increased risk for breast cancer (BC). Considering the high incidence of BC in the city of Porto Alegre in southern Brazil, the purpose of this study was to characterize genotypic and allelic frequencies of polymorphisms in GSTM1, GSTT1, and GSTP1, and correlate these molecular findings with established risk factors for breast cancer including mammographic density, in a sample of 750 asymptomatic women undergoing mammographic screening. Molecular tests were performed using the multiplex polymerase chain reaction (PCR) for GSTM1 and GSTT1, and quantitative PCR for GSTP1 polymorphisms. Overall, the frequencies of GSTM1 and GSTT1 null genotypes were 45% and 21%, respectively. For GSTP1 polymorphism, genotypic frequencies were 44% for the Ile/Ile genotype, 44% for the Ile/Val genotype, and 12% for Val/Val genotype, with an allelic frequency of 66% for the wild type allele in this population, similar to results of previous international publications. There was a statistically significant association between the combined GSTM1 and GSTT1 null genotypes (M-/T-) and mammographic density in post menopausal women (p = 0.031). When the GSTT1 null (T-) genotype was analyzed isolated, the association with mammographic density in post menopausal women and in the overall sample was also statistically significant (p = 0.023 and p = 0.027, respectively). These findings suggest an association of GSTM1 and GSTT1 null genotypes with mammographic density.

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.

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.

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. (c) 2009 Wiley-Liss, Inc.