Rapid screening method for detecting mutations in the 21-hydroxylase gene.

Impaired synthesis of adrenal steroid hormones because of steroid 21-hydroxylase deficiency is one of the most common inborn errors of metabolism. To expedite molecular diagnosis in families with 21-hydroxylase deficiency, we have designed a rapid strategy to determine nine of the most common mutations in the 21-hydroxylase gene. According to the mutation to be detected, we apply either of two simple strategies: digestion with adequate restriction enzyme or use of the amplification-created restriction site (ACRS) approach and subsequent restriction analysis. Both procedures are rapid and, being nonradioactive, are safer to perform; moreover determination of zygosity in the analyzed mutations requires only one tube per mutation.

[Familial study for the early diagnosis of insulin-dependent diabetes mellitus]. / Estudio familiar para el diagnóstico temprano de la diabetes mellitus insulinodependiente.

BACKGROUND: Diabetes is more frequently found than expected in families of first grade with children with diabetes type I. METHODS: With the aim of identifying the potential candidates prone to develop diabetes type I, genetic and metabolic analysis was carried out on the members of 11 families with a diabetic type I child. They were distributed into three groups: 11 diabetic patients (IDDM); 22 progenitors and 13 unaffected siblings. The HLA haplotype was determined, the spectrum of autoantibodies and the intravenous glucose tolerance test (IVTT) were performed. RESULTS: In two progenitors postprandial glycemia values corresponding to intolerance to carbon hydrates were obtained. Moreover, in one the IVTT was found to be low in the normal values. Of a total of 12 non diabetic descendents studied, 4 shared identical HLA haplotypes as the diabetic, 5 were haploidentical and 3 unidentical. The DR 3 antigen was detected in 90% of the diabetics; in 68% of the progenitor group and in 50% of the non diabetic descendents. Sixty-two percent of the children inherited the DR 4 antigen of the father (p less than 0.05), while 37% do so from the mother. Of the siblings with a haplotype identical to that of the diabetic, 2 were also ICA positive; asymptomatic at the moment of the study but in one the diabetes type I became manifest after 2 years of evolution. CONCLUSIONS: Subjects at high risk of becoming type I diabetics may be identified at a preclinical phase by means of HLA typing and the detection of immunologic and metabolic markers associated with the disease.

[Susceptibility to chronic HLA-system-associated lymphocytic thyroiditis. Its relationship with insulin-dependent diabetes mellitus]. / Susceptibilidad a tiroiditis crónica linfocitaria asociada al sistema HLA. Su relación con la diabetes mellitus insulinodependiente.

The genetic association between HLA-system and chronic lymphocytic thyroiditis (CLT) related or not to type I diabetes mellitus (IDDM), have been analysed in three groups of children: 16 with CLT, 9 with CLT and IDDM, 11 with IDDM and 200 normal controls. The DQw1 antigen (75% vs 55%) was found associated with CLT, furthermore the observed increase of DR1 and DR2 antigens (37% respectively) is secondary to the linkage disequilibrium that exists between them and DQw1. DR3 antigen (60%) was found significantly increased (p less than 0.001) in CLT patients compared with the control group (24%). In diabetic patients, DR3 and DR4 were found in 85% and 63% respectively (p less than 0.001). The DR3 associated haplotype in CLT patients was different from the diabetic one's. All the diabetics, but one, were DR3-B18 haplotype carriers, but this association was only found in 25% CLT patients. The titre of thyroid microsomal antibodies (MCHA) was more frequent in the patients with DQw1 antigen (MCHA DQw1+ : 1/1072; DQw1- : 1/606). The CLT predisposition in childhood may be influenced by genes located within the HLA-region probably more than one, different from the genes related to IDDM. One of this genes closed to the HLA-DQ region, will be involved in the production of autoantibodies.