Camila Andréa de Oliveira

Deafness resulting from mutations in the GJB2 (connexin 26) gene in Brazilian patients

Congenital deafness occurs in approximately 1 in 1000 live births. In developed countries about 60% of hearing loss is genetic. However, in Brazil most cases of hearing loss are due to environmental factors, such as congenital infections (mainly rubella), perinatal anoxia, kernicterus and meningitis. Recently, it has been demonstrated that the GJB2 gene is a major gene underlying congenital sensorial deafness. Mutations in this gene cause 10–20% of all genetic sensory hearing loss. One specific mutation, 35delG, accounts for the majority of mutant alleles. The extent of the hearing impairment varies from mild/moderate to profound, even within the patients homozygous for the common 35delG mutation. There may also be progression with age. Mutation analysis in the GJB2 gene was performed on 36 families (group A) presenting with at least one individual with non‐syndromic deafness (NSD). An unselected series of 26 deaf individuals referred by other services where the environmental factors were not completely excluded was also part of the study (group B).

Taurine supplementation restores glucose and carbachol-induced insulin secretion in islets from low-protein diet rats: involvement of Ach-M3R, Synt 1 and SNAP-25 proteins.

Isolated islets from low-protein (LP) diet rats showed decreased insulin secretion in response to glucose and carbachol (Cch). Taurine (TAU) increases insulin secretion in rodent islets with a positive effect upon the cholinergic pathway. Here, we investigated the effect of TAU administration upon glucose tolerance and insulin release in rats fed on a normal protein diet (17%) without (NP) or with 2.5% of TAU in their drinking water (NPT), and LP diet fed rats (6%) without (LP) or with TAU (LPT). Glucose tolerance was found to be higher in LP, compared to NP rats. However, plasma glucose levels, during ipGTT, in LPT rats were similar to those of controls. Isolated islets from LP rats secreted less insulin in response to increasing glucose concentrations (2.8-22.2 mmol/L) and to 100 μmol/L Cch. This lower secretion was accompanied by a reduction in Cch-induced internal Ca(2+) mobilization. TAU supplementation prevents these alterations, as judged by the higher secretion induced by glucose or Cch in LPT islets. In addition, Ach-M3R, syntaxin 1 and synaptosomal associated protein of 25 kDa protein expressions in LP were lower than in NP islets. The expressions of these proteins in LPT were normalized. Finally, the sarcoendoplasmatic reticulum Ca(2+)-ATPase 3 protein expression was higher in LPT and NPT, compared with controls. In conclusion, TAU supplementation to LP rats prevented alterations in glucose tolerance as well as in insulin secretion from isolated islets. The latter effect involves the normalization of the cholinergic pathway, associated with the preservation of exocytotic proteins.

Molecular genetics study of deafness in Brazil: 8-year experience.

Hereditary hearing loss is a complex disorder that involves a large number of genes. In developed countries, 1 in 1,000 children is born with deafness severe enough to require special education services, and about 60% of the cases of isolated deafness have a genetic origin. Although more than 100 genes for hearing loss are known currently, only a few are routinely tested in the clinical practice. In this study, we present our findings from the molecular diagnostic screening of the GJB2 and GJB3 genes, del(GJB6‐D13S1830) and del(GJB6‐D13S1854) deletions in the GJB6 gene, Q829X mutation in the otoferlin gene (OTOF) and, the A1555G and A7445G mutations in the mitochondrial genome over an 8‐year period. Mutations analysis in the previously mentioned genes and mutations was performed on 645 unrelated Brazilian patients with hearing loss who fell into two different testing groups. Different mutations in the GJB2 gene were responsible for most of cases studied, but deletions in the GJB6 gene as well as mitochondrial mutations were also found. While most cases of hearing loss in this country are due to environmental factors, the genetic etiology of deafness will increasingly be determined as more genetic tests become available.

Genética molecular da deficiência auditiva não-sindrômica

One in every 1,000 newborn suffers from congenital hearing impairment. More than 60% of the congenital cases are caused by genetic factors. In most cases, hearing loss is a multifactorial disorder caused by both genetic and environmental factors. Molecular genetics of deafness has experienced remarkable progress in the last decade. Genes responsible for hereditary hearing impairment are being mapped and cloned progressively. This review focuses on non-syndromic hearing loss, since the gene involved in this type of hearing loss have only recently begun to be identified.

Molecular genetics of non-syndromic deafness

One in every 1,000 newborn suffers from congenital hearing impairment. More than 60% of the congenital cases are caused by genetic factors. In most cases, hearing loss is a multifactorial disorder caused by both genetic and environmental factors. Molecular genetics of deafness has experienced remarkable progress in the last decade. Genes responsible for hereditary hearing impairment are being mapped and cloned progressively. This review focuses on non-syndromic hearing loss, since the gene involved in this type of hearing loss have only recently begun to be identified.

Estudo epidemiológico do HPV na mucosa oral por meio de PCR

The Human Papillomavirus (HPV) belongs to the Papillomaviridae family and has a capsid and a single DNA strand. Its infection occurs mainly through sexual intercourse, having an important tropism for skin and mucosal cells. AIM: To evaluate the HPV presence in normal oral mucosa of asymptomatic subjects and; in parallel, to correlate social behavioral habits with the virus. MATERIALS AND METHODS: Contemporary cohort cross-sectional study. The HPV was found by PCR, using general primers MY09/11 in 125 oral mucosa samples submitted to DNA extraction and PCR to search for the beta-globin gene in order to assess the quality of the extracted DNA. In parallel, we carried out a study of behavioral issues associated with the patients. RESULTS: All the samples had a positive diagnosis of the beta-hemoglobin gene. HPV was diagnosed in 23.2% of the samples analyzed. CONCLUSION: The virus was present in 29 of the 125 patients, without them having any clinical-pathological manifestation associated with the HPV. As to the social behavior of the patients, we concluded that oral sex is statistically correlated to the virus, and besides the HPV has been statistically more present in female patients.UNLABELLED The Human Papillomavirus (HPV) belongs to the Papillomaviridae family and has a capsid and a single DNA strand. Its infection occurs mainly through sexual intercourse, having an important tropism for skin and mucosal cells. AIM To evaluate the HPV presence in normal oral mucosa of asymptomatic subjects and; in parallel, to correlate social behavioral habits with the virus. MATERIALS AND METHODS Contemporary cohort cross-sectional study. The HPV was found by PCR, using general primers MY09/11 in 125 oral mucosa samples submitted to DNA extraction and PCR to search for the beta-globin gene in order to assess the quality of the extracted DNA. In parallel, we carried out a study of behavioral issues associated with the patients. RESULTS All the samples had a positive diagnosis of the beta-hemoglobin gene. HPV was diagnosed in 23.2% of the samples analyzed. CONCLUSION The virus was present in 29 of the 125 patients, without them having any clinical-pathological manifestation associated with the HPV. As to the social behavior of the patients, we concluded that oral sex is statistically correlated to the virus, and besides the HPV has been statistically more present in female patients.

Prospects for genetic hearing loss screening: 35delG mutation tracking in a newborn population

OBJECTIVES: To investigate the prevalence of the 35delG mutation in a newborn population, with specific molecular testing, and to evaluate the prospects for genetic neonatal screening for hearing impairment. POPULATION AND METHOD: 233 newborn were evaluated at the Hospital de Base de Sao Jose do Rio Preto, SP, for molecular analysis of the 35delG mutation in the connexin 26 gene, with the reaction technique in allele-specific polymerase chain reaction, after genomic DNA extraction from umbilical cord blood. RESULTS: Five heterozygotes were identified, obtaining a prevalence of 2.24% of 35delG mutation carriers in the study population. CONCLUSION: Using the molecular test allowed for the identification of the 35delG mutation in the study population with the possibility of being used as a complement to neonatal audiometric screening as being simple, fast, and easily to perform with low costs.

Newborn hearing screening and genetic testing in 8974 Brazilian neonates

OBJECTIVE An early diagnosis has been a priority in the audiological practice. Identifying hearing loss until 3 months old through Universal Newborn Hearing Screening and intervention before 6 months old, minimize the impact of auditory loss in the health and communication development of these children. However, in the clinical practice, despite the help of the risk indicators in the audiological and etiological diagnosis, the integrated services have come up against the challenge of determining the causes of auditory loss, bearing in mind that approximately 50% of the subjects who have congenital loss do not show risk factors in their clinical history. The current research aims introduce together etiologic and audiological diagnosis of newborns. METHODS We eluted dried blood spots from paper and performed genetic testing for 35delG mutation in 8974 newborns that were also screened for transient otoacoustic emissions (TOAE). In addition, the A1555G and A827G mutations in the MTRNR1 mitochondrial gene were screened in all newborns. RESULTS We have found 17 individuals who failed in TOAE. Among them, we detected 4 homozygous newborns for 35delG mutation and 3 individuals with A827G mutation in the MTRNR1 mitochondrial gene. The frequency of 35delG carriers was 0.94% [84/8974]. In all 17 individuals who failed in OAE no other mutation besides those mentioned above was found. CONCLUSIONS The results greatly contribute to the public health area indicating the etiologic diagnosis, allowing family counseling as well as the early rehabilitation treatment or surgical intervention. Over time that will help to reduce the costs of rehabilitation considerably.

Leucine Supplementation Augments Insulin Secretion in Pancreatic Islets of Malnourished Mice

Objectives: We investigated the influence of leucine supplementation on insulin secretion and on some proteins related to insulin secretion in malnourished mice. Methods: Swiss mice (aged 21 days) received isocaloric normo-17% (NP) or 6% low-protein (LP) diet for 120 days. Half of the NP and LP mice received 1.5% leucine in the drinking water during the last 30 days (NPL and LPL, respectively). Results: The LP mice were hypoinsulinemic compared with the NP group, whereas LPL mice exhibited increased insulinemia in the fed state versus LP mice. The LP mouse islets were less responsive to 22.2 mM glucose, 100 &mgr;M carbachol (Cch), and 10 mM leucine than the NP group. However, LPL islets were more responsive to all these conditions compared with the LP group. The muscarinic type 3 receptor, (M3R) Ca&bgr;2, and PKC-&agr; protein contents were reduced in LP compared with NP islets but significantly higher in LPL than LP islets. The p-AKT/AKT ratio was higher in LPL compared with LP islets. Conclusions: Leucine supplementation increases insulin secretion in response to glucose and leucine and to agents that potentiate secretion, such as Cch, in malnourished mice. The enhanced levels of M3R, Ca&bgr;2, and PKC-&agr; proteins, as well as of the p-AKT/AKT ratio, may play a role in this process.

Connexin mutations in Brazilian patients with skin disorders with or without hearing loss.

The connexins are a family of proteins whose major function is as part of the gap junctions of cell‐to‐cell channels. They are expressed in several tissues including brain, skin, and cochlea. Mutations in connexin genes play a major role in non‐syndromic sensorineural deafness, but have been also described in individuals with variable dermatological features. In recent years, many genes responsible for hereditary skin diseases have been discovered. These genes may encode different proteins that participate in the terminal differentiation of the epidermis. Therefore alteration or absence of these proteins causes a keratinization disorder. It has been demonstrated that distinct germline mutations within six connexin (Cx) genes GJB2 (Cx26), GJB6 (Cx30), GJB3 (Cx31), GJA1 (Cx43), GJB4 (Cx30.3), and GJB5 (Cx31.1), may cause sensorineural hearing loss and various skin disease phenotypes. The crucial functional importance of each of these connexins in the mentioned ectodermic tissues is reflected by the finding that genetic defects in their genes produce a wide spectrum of genetic disorders comprising sensorineural hearing loss, disorders of cornification of the skin, hair, and nails, and keratitis. Here, we report on different mutations in the connexin genes in individuals with or without hearing loss and different skin disorders illustrating the clinical and genetic heterogeneity of the condition.