Pediatria pre prax 3/2012

New diagnostic tools in mental retardation

Mental retardation in children and adults is a serious medical and social problem. There are many causes of mental retardation, but specific reason is found in only 25 % of cases. Recent progress in cytogenetic methods explained etiology of 10 % before unexplained mental retardation due to detection of subtelomeric rearrangements, not visible by conventional cytogenetic analysis. The authors refer about this modern diagnostic tools and present a case report of 4-years-old boy, who was investigated since infancy because of clinical symptoms of severe mental retardation. Only at the age of 4 years, when multiprobe FISH method was introduced to specify genetic diagnostic the authors were able to identify the subtelomeric deletion of chromozome 8 and telomeric trisomy of chromozome 12 – deletion in subtelomeric area 8p and trisomy in telomeric area 12p, which the child inherited from his healthy mother. Cytogenetic examination of subtelomeric rearrangement of chromozomes provide only two hospitals in Czech Republic – our department in Ostrava and Department of Biology and Medical Genetics University hospital Motol and 2nd Faculty of Medicine, Charles University Prague.

Keywords: mental retardation, cytogenetic methods, FISH, subtelomeric rearrangement of chromozomes.