Búsqueda de afecciones genéticas como etiología de déficit intelectual en individuos que asisten a escuelas de educación especial

Abstract

Background:Mental retardation or intellectual disability affects 2% of the general population, but in 60% to 70% of cases the real cause of this retardation is not known. An early etiologic diagnosis of intellectual disability can lead to opportunities for improved educational interventions, reinforcing weak areas and providing a genetic counseling to the family. Aim: To search genetic diseases underlying 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 tandem 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 (Rev Méd Chile 2008; 136: 1542-51). (

Caracterización citogenético molecular de enfermedades genéticas en el Hospital Base de Puerto Montt

“…Este es el primer estudio en Chile que muestra alteraciones detectadas con estudios moleculares, en un número importante de casos, todos ellos atendidos en el sistema público de salud de la X Región; además avala la importancia de hacer análisis más resolutivos en pacientes con fenotipos sugerentes de afecciones genéticas, tal como había sido descrito recientemente 10,11,18 .…”

“…La obtención de cromosomas se realizó en el Laboratorio Clínico del HBPM; el recuento, microfotografías y análisis del cariotipo se realizaron en el Laboratorio de Citogenética del INTA, utilizando metodología previamente publicada 18 .…”

“…Considerando que las aberraciones cromosómicas son la principal causa etiológica de DI, especialmente en los grados moderado a severo, es que el DI es otra de las principales indicaciones para análisis cromosómico y búsqueda de mutaciones relativamente frecuentes, como las responsables de los síndromes X frágil, Prader Willi y Angelman, entre otros. Identifi car la etiología de estas alteraciones permite el inicio precoz del manejo clínico adecuado, la estimulación sensorial y motora dirigida; además conocer el pronóstico y riesgo de recurrencia de la afección, así como también poder entregar asesoría genética reproductiva oportuna a los padres y otros familiares a riesgo [16][17][18] .…”

Cytogenetic Diagnosis and Analysis of the Clinical Profile of Individuals with Non-down Syndrome Intellectual Disability

“…Each 5 mL sample of blood was transferred to two duly identified heparinized tubes and placed in a vertical position at room temperature in the sterile laminar flow cabinet. Next, 500 μL of whole peripheral blood were placed in complete culture medium composed of 8 For the chromosome analysis the G banding technique [12] with modifications was used. The karyotype analysis was performed using a NIKON Eclipse E200 light microscope, with an average 20 to 30 metaphases per individual observed, in cases of suspected mosaicism this number increased to 50.…”

“…In Special Education Schools in Santiago, Chile, Alliende et al [8] conducted a study including 103 individuals with non-Down syndrome ID, of whom only one had an etiologic diagnosis. In another study by Abreu [9], carried out in three APAES of the Rio Preto region of São Paulo, 12.1% of individuals affected by ID had chromosomal abnormalities, of which 90.2% were numerical, mostly trisomy 21.…”