[Genetic analysis of RET mutations in families with multiple endocrine neoplasia type II in the community of Murcia]. / Análisis genético de las mutaciones de RET en las familias con neoplasia endocrina múltiple tipo 2 de la Comunidad de Murcia.

BACKGROUND: Multiple endocrine neoplasia type 2 (MEN 2) syndromes are inherited following an autosomal dominant pattern. RET protooncogen mutations have been associated with MEN 2. The identification of these mutations enables us to diagnose MEN 2. The objectives were to recognize RET mutations and gene carriers in the area of Murcia and to sep up the relationship between genotype and phenotype. PATIENTS AND METHODS: 284 subjects from 14 MEN 2A kindreds and one MEN 2B family from the Community of Murcia, Spain, were studied. 48 out of them had MEN 2 tumours and 236 subjects were at risk. The initial screening test was single-strand conformation polymorphism (SSCP) in 8 MEN 2A families and denaturing gradient gel electrophoresis (DGGE) in 6 MEN 2A families; the results in all the subjects were confirmed with restriction analysis. The MEN 2A family in which the Cfo-I enzyme detected but did not specify the type of mutation received DNA sequence assay. The MEN 2B kindred was studied with restriction analysis. RESULTS: TGC-->TAC and TGC-->CGC mutations of codon 634 were found in 13 and one MEN 2A kindreds, respectively. ATG-->ACG mutation of codon 918 was present in the MEN 2B family. Clinical diagnosis was confirmed in the 48 patients, 44 new gene carriers were detected and 192 carriers of normal alleles were ruled out. The incidence of hyperparathyroidism was highest if RET mutation was TGC-->CGC. CONCLUSIONS: Community of Murcia is one of the areas with the highest prevalence of MEN 2. The risk of hyperparathyroidism is increased if TGC-->CGC is present.

[A genetic and molecular study of 85 families affected with the fragile X syndrome]. / Estudio genético y molecular de 85 familias afectas del síndrome del cromosoma X frágil.

The objective of this study was to analyze clinically, cytogenetically and molecularly 85 Spanish families with fragile X syndrome. Clinical studies were based on the score proposed by Hagerman, cytogenetic studies were made by adding. 5-fluorodeoxiuridine and molecular studies were performed by using a StB12.3 probe and the polymerase chain reaction (PCR). The results of the molecular studies in 620 individuals at risk confirmed the clinical diagnosis of fragile X syndrome in 126 affected males. In addition, 197 carrier females were detected (48 with mental retardation) and 246 "at risk" individuals and 36 non-related members were found not to have the expansion. Fifteen cases of normal transmitting males (NTM) were detected. We found one non-mentally retarded male where the CpG island of the FMR-1 gene was not methylated, but with more than 200 (CGG)n repeats (high functioning male). In the sample studied, no de novo mutations were found and all of the mutations detected were (CGG)n expansions. PCR analysis of the (CGG)n repeat in 297 normal chromosomes showed an allele distribution that ranged from 17 to 54 repeats, with an allele of 29 (CGG)n repeats accounting for 24% of the chromosomes. In conclusion, molecular genetic study of fragile X provides accurate diagnosis and facilitates genetic counselling in families with affected members. Southern blot analysis and PCR of the (CGG)n repeat provides efficient diagnosis, compared to cytogenetic techniques, for the detection of female carriers, NTMs, and prenatal diagnosis.