Comprehensive germline mutation analysis and clinical profile in a large cohort of Brazilian xeroderma pigmentosum patients.

BACKGROUND: Xeroderma pigmentosum (XP) patients present a high risk of developing skin cancer and other complications at an early age. This disease is characterized by mutations in the genes related to the DNA repair system. OBJECTIVES: To describe the clinical and molecular findings in a cohort of 32 Brazilian individuals who received a clinical diagnosis of XP. METHODS: Twenty-seven families were screened for germline variants in eight XP-related genes. RESULTS: All patients (N = 32) were diagnosed with bi-allelic germline pathogenic or potentially pathogenic variants, including nine variants previously undescribed. The c.2251-1G>C XPC pathogenic variant, reported as the founder mutation in Comorian and Pakistani patients, was observed in 15 cases in homozygous or compound heterozygous. Seven homozygous patients for POLH/XPV variants developed their symptoms by an average age of 7.7 years. ERCC2/XPD, DDB2/XPE and ERCC5/XPG variants were found in a few patients. Aside from melanoma and non-melanoma skin tumours, a set of patients developed skin sebaceous carcinoma, leiomyosarcoma, angiosarcoma, mucoepidermoid carcinoma, gastric adenocarcinoma and serous ovarian carcinoma. CONCLUSIONS: We reported a high frequency of XPC variants in 32 XP Brazilian patients. Nine new variants in XP-related genes, unexpected non-skin cancer lesions and an anticipation of the clinical manifestation in POLH/XPV cases were also described.

A Multicentric Brazilian Investigative Study of Copy Number Variations in Patients with Congenital Anomalies and Intellectual Disability.

Genomic imbalances are the most common cause of congenital anomalies (CA) and intellectual disability (ID). The aims of this study were to identify copy number variations (CNVs) in 416 patients with CA and ID from 5 different genetics centers within 4 different states by using the Multiplex Ligation-dependent Probe Amplification (MLPA) technique and to apply the chromosomal microarray (CMA) methodology in selected cases. The samples were analyzed by MLPA kits P064, P036, P070 and P250. Positive results were found in 97/416 (23.3%) patients. CMA was applied in 14 selected cases. In 6/14 (42.85%) patients, CMA detected other copy number variations not detected by the MLPA studies. Although CMA is indispensable for genotype refinement, the technique is still unfeasible in some countries as a routine analysis due to economic and technical limitations. In these cases, clinical evaluation followed by karyotyping and MLPA analysis is a helpful and affordable solution for diagnostic purposes.

Insecticide resistance, associated mechanisms and fitness aspects in two Brazilian Stegomyia aegypti (= Aedes aegypti) populations.

In Brazil, insecticide resistance in Stegomyia aegypti (= Aedes aegypti) (Diptera: Culicidae) populations to pyrethroids and to the organophosphate (OP) temephos is disseminated. Currently, insect growth regulators (IGRs) and the OP malathion are employed against larvae and adults, respectively. Bioassays with mosquitoes from two northeast municipalities, Crato and Aracaju, revealed, in both populations, susceptibility to IGRs and malathion (RR95 ≤ 2.0), confirming the effectiveness of these compounds. By contrast, temephos and deltamethrin (pyrethroid) resistance levels were high (RR95 > 10), which is consistent with the use of intense chemical control. In Crato, RR95 values were > 50 for both compounds. Knock-down-resistant (kdr) mutants in the voltage-gated sodium channel, the pyrethroid target site, were found in 43 and 32%, respectively, of Aracaju and Crato mosquitoes. Biochemical assays revealed higher metabolic resistance activity (esterases, mixed function oxidases and glutathione-S-transferases) at Aracaju. With respect to fitness aspects, mating effectiveness was equivalently impaired in both populations, but Aracaju mosquitoes showed more damaging effects in terms of longer larval development, decreased bloodmeal acceptance, reduced engorgement and lower numbers of eggs laid per female. Compared with mosquitoes in Crato, Aracaju mosquitoes exhibited lower OP and pyrethroid RR95 , increased activity of detoxifying enzymes and greater effect on fitness. The potential relationship between insecticide resistance mechanisms and mosquito viability is discussed.

Array-CGH analysis in patients with intellectual disability and/or congenital malformations in Brazil.

In several patients, intellectual disability and/or congenital malformation may be attributed to chromosomal changes. In this study, we conducted an array-CGH test of 200 patients from the Northeast of Brazil with intellectual disability and/or congenital malformation. Blood samples were collected from the proband and from their parents when possible. DNA was extracted and investigated using the array-CGH test. Findings were evaluated for the pathogenicity in databases of benign and pathogenic changes (ISCA, UCSC, DGV, and DECIPHER). Forty-seven copy number variations (CNVs) were identified in 43/200 (21.5%) patients, including 25/98 (25.5%) in males and 22/102 (21.57%) in females. We considered 33 of these to be clinically significant, reaching a diagnosis rate of 16.5%. The sizes of the CNVs varied from 102 kb to 24 Mb in deletions and from 115 kb to 140 Mb in duplications. In 10/47 (21.3%) patients, the rearrangement involved a sex chromosome. Thirty-nine patients had one chromosomal aberration, while 2 concomitant abnormalities were detected in 4 patients. Ten of 47 CNVs (21.3%) were > 5Mb in size. Fifteen patients had CNVs related to known syndromes. This research highlights the contribution of submicroscopic chromosomal changes to the etiology of intellectual disability and/or congenital malformation, particularly the implication of chromosomal abnormalities detected using an array-CGH test, with a high rate of 16.5%. Thus, our results support the use of array-CGH replacing standard karyotype as the first-tier cytogenetic diagnostic test for patients with multiple congenital anomalies and/or intellectual disability.

Laryngeal atresia type III (glottic web) with 22q11.2 microdeletion: report of three patients.

The clinical manifestations of patients with a 22q11.2 deletion are highly variable and mainly include developmental defects of structures derived from the third and fourth pharyngeal pouches. Laryngeal atresia has occasionally been reported in DiGeorge syndrome as well as in velo-cardio-facial syndrome. We observed three patients with type III laryngeal atresia (glottic web) and 22q11.2 microdeletion. One patient showed a "classical" 22q11.2 deletion phenotype with clinical overlap with DiGeorge and velo-cardio-facial syndromes. However, the pattern of congenital anomalies of the two others was less specific, heart defects and minor anomalies being the only outstanding clinical manifestations suspicious for monosomy 22q11.2. Our findings suggest that laryngeal atresia represents an additional malformation which should prompt investigation of 22q11.2 deletion, especially in combination with congenital heart defects.