Búsqueda de afecciones genéticas como etiología de déficit intelectual en individuos que asisten a escuelas de educación especial / Genetic screening to determine an etiologic diagnosis in children with mental retardation

Background: Mental retardation or intellectual disability affects 2 percent ofthe general population, but in 60 percent to 70 percent of cases the real cause ofthis retardation is not known. An early etiologic diagnosis of intellectual disability can lead to opportunities for improved educational interventions, reinforcing weak aáreas and providing a genetic counseling to the family Aim: To search genetic diseases underíying intellectual disabilities of children attending a special education school. Material and methods: A clinical geneticist performed the history and physical examination in one hundred and three students aged between 5 and 24 years (51 males). A blood sample was obtained in 92 of them for a genetic screening that included a standard karyotype, fragile X molecular genetic testing and search for inborn errors of metabolism by tándem mass spectrometry. Results: This approach yielded an etiological diagnosis in as much as 29 patients. Three percent of them had a fragile X syndrome. Inborn errors of metabolism were not detected. Conclusions: This type of screening should be done always in children with intellectual disability to establish an etiological diagnosis.

Ingeniería genética en hongos filamentosos: clonamiento del gen de invertasa de neurospora crassa / Genetic engineering in filamentous fungi: cloning of the invertase gene from Neurospora crassa

The invertase wild type gene of N. crassa was cloned into the YRp7 yeast vector. This recombinant plasmid was selected by functional complementation of an invertaseless mutant strain of S. cerevisiae. The isolated recombinant plasmid (named pNC2) carries a 7.6 Kb BamHI DNA fragment from N. crassa. The cloned DNA hydbridized with the N. crassa genomic DNA and transformed an invertase mutant of N. crassa Inv- to Inv+. Transformation of N. crassa Inv- to Inv+ seems to take at least two different integration events. One of them involves an integration closely linked to inv locus, and the other one apparently involves as integration of cloned DNA at a genomic site different that the inv locus