Frequency of FMR1 premutation in individuals with ataxia and/or tremor and/or parkinsonism

A late onset neurological syndrome in carriers of premutation in FMR1 gene was recently described. The condition was named fragile-X-associated tremor/ataxia syndrome (FXTAS) and includes intentional tremor, cerebellar ataxia, parkinsonism, and cognitive deficit. We ascertained the contribution of FMR1 premutation to the phenotypes ataxia, tremor and/or parkinsonism. Sixty-six men over 45 years old presenting these symptoms, isolated or combined, were tested. Also, 74 normal men, randomly chosen in the population, formed the control group. In the patient group, no premutation carrier was found, which is in agreement with other observed frequencies reported elsewhere (0-5% variation). No significant differences were found when comparing gray zone allele frequencies among target and control groups. The FXTAS contribution in patients with phenotypic manifestations of FXTAS was 15/748 (2%). The presence of gray zone alleles is not correlated with FXTAS occurrence.

Determinação do sexo do feto através de uma nova técnica não invasiva baseada em PCR / Determination of fetal sex by a new PCR method non invasive

A determinação do sexo do feto é geralmente realizada pelo procedimento de ultra-som que ocorre no segundo trimestre da gestação, sendo que, quando realizado antes da 13ª semana, esse método se mostra muito incerto.Técnicas moleculares utilizando o PCR já foram descrita, e possuem maior sensibilidade na determinação do sexo. Dentre estas técnicas existentes, as invasivas consistem em amniocentese ou coleta de amostra de vilo coriônico, seguida de PCR para determinar osexo e que representam em aumento de risco na gravidez e as técnicas não invasivas que conseguem detectar o DNA fetal no sangue periférico materno. Foi desenvolvida em nosso laboratório uma técnica capaz de detectar o sexo fetal nas primeiras semanas de gestaçãocom alto índice de acerto. A técnica consistiu em desenhar iniciadores que anelassem em regiões repetitivas espalhadas no cromossomoY e “PCR Nested” para aumentar a acurácia do exame. Os resultados demonstraram que a técnica possui sensibilidade e especificidade de 100%. Além disso, a PCR foi capaz de detectar em uma diluição seriada de uma amostra de DNA genômico masculina, previamente quantificada, a presença do cromossomo Y em amostrascontendo apenas 100 femtogramas de DNA.

The determination of fetal sex is currently carried out by ultrasound that is usually performed in the second trimester. However, it is inaccurate before 13th week of gestation. Molecular techniques such as PCR already had been described and were successful of fetal gender. Among these techniques, there are invasive methods: chorionic villus sampling and amniocentesis that are avoided because it is associated with a risk of fetal loss, and the non-invasive procedures that use of fetal DNA circulating in maternal blood. We report a new Nested PCR method with specific primers for repetitive sequences of the Y-chromossome. Our results indicated that sensitivity and specificity of the method were 100% and we can accurately detect Y-chromossome sequences in samples with only 100 femtograms of DNA template.

Frequency of islet cell autoantibodies (IA-2 and GAD) in young Brazilian type 1 diabetes patients

Type 1 diabetes, as an autoimmune disease, presents several islet cell-specific autoantibodies such as islet cell antibody (ICA), anti-insulin, anti-glutamic acid decarboxylase (GAD) and the antibody (Ab) against tyrosine phosphatase (PTP)-like protein known as ICA-512 (IA-2). In order to determine the frequency of the anti-GAD and anti-IA-2 autoantibodies in Brazilian type 1 diabetes patients we studied 35 diabetes mellitus (DM) type 1 patients with recent-onset disease 12 months and 37 type 1 diabetes patients with long-duration diabetes 12 months who were compared to 12 children with normal fasting glucose. Anti-GAD65 and anti-IA-2 autoantibodies were detected with commercial immunoprecipitation assays. The frequency of positive results in recent-onset DM type 1 patients was 80.0 percent for GADAb, 62.9 percent for IA-2Ab and 82.9 percent for GADAb and/or IA-2Ab. The long-duration type 1 diabetes subjects presented frequencies of 54.1 percent for GADAb and IA-2Ab, and 67.5 percent for GAD and/or IA-2 antibodies. The control group showed no positive cases. Anti-GAD and IA-2 assays showed a high frequency of positivity in these Brazilian type 1 diabetes patients, who presented the same prevalence as a Caucasian population

Fetal hemoglobin levels are related to metabolic control in diabetic subjects

We have investigated the relationship between fetal hemoglobin (HbF) levels and metabolic control in subjects with insulin-dependent (N = 79) and non-insulin-dependent diabetes mellitus (N = 242). HbF and hemoglobin A1c (HbA1c) levels were increased in subjects with type 1 and type 2 diabetes as compared to levels in nondiabetic individuals (P<0.0001), and were significantly higher in type 1 than in type 2 diabetes subjects. Lower levels of HbA1c and HbF were observed in type 2 diabetes subjects treated by diet, intermediate levels in those treated with oral hypoglycemic agents, and higher levels in those treated with insulin. HbF and HbA1c levels were correlated in type 1 diabetes (R2 = 0.57, P<0.0001) and type 2 diabetes (R2 = 0.58, P<0.0001) subjects. Following intense treatment, twelve diabetic patients showed significant improvement both in HbA1c and HbF values. We conclude that increased HbF levels reflect poor metabolic control in subjects with diabetes mellitus.

Specific insulin and proinsulin secretion in glucokinase-deficient individuals

Glucokinase (GCK) is an enzyme that regulates insulin secretion, keeping glucose levels within a narrow range. Mutations in the glucokinase gene cause a rare form of diabetes called maturity-onset diabetes of the young (MODY). An early onset (less than 25 years), autosomal dominant inheritance and low insulin secretion stimulated by glucose characterize MODY patients. Specific insulin and proinsulin were measured in serum by immunofluorimetric assays (IFMA) during a 75-g oral glucose tolerance test (OGTT). Two kindreds (SA and LZ) were studied and compared to non-diabetic unrelated individuals (control group 1) matched for age and body mass index (BMI). In one kindred, some of these subjects were also obese (BMI>26 kg/m2), and other family members also presented with obesity and/or late-onset NIDDM. The MODY patients were also compared to a group of five of their first-degree relatives with obesity and/or late-onset NIDDM. The proinsulin profile was different in members of the two MODY kindreds. Fasting proinsulin and the proinsulin/insulin ratio were similar in MODY members of kindred LZ and subjects from control group 1, but were significantly lower than in MODY members of kindred SA (P<0.02 and P<0.01, for proinsulin and proinsulin/insulin ratio, respectively). Moreover, MODY members of family SA had higher levels of proinsulin and proinsulin/insulin ratio, although not significantly different, when compared to their first-degree relatives and to subjects from control group 2. In conclusion, we observed variable degrees of proinsulin levels and proinsulin/insulin ratio in MODY members of two different kindreds. The higher values of these parameters found in MODY and non-MODY members of kindred SA is probably related to the obesity and late-onset NIDDM background present in this family.