Rodríguez-Revenga Bodi L, Madrigal-Bajo I, Milà-Racasens M
Hospital Clinic de Barcelona, 08036 Barcelona, Espana.
Rev Neurol. 2006 Oct 10;43 Suppl 1:S181-6.
Mental retardation is a frequently occurring disorder with a major impact on the life of the affected person, the family and society, with an estimated incidence of 1-3% in developed countries. Among the etiologies that cause mental retardation it would appear that 30% have a genetic origin, 15% have an environmental origin, and the rest have an unknown origin. AIM. To report the genetic causes of mental retardation and the new molecular techniques used in order to reach a diagnosis. The identification of the causes of mental retardation is of great interest due to the consequences it has in the intervention, prognosis, estimation of risk of recurrence and its prevention.
Causes of mental retardation are extremely heterogeneous. Genetic causes can be classified as chromosomal alterations (aneuploidies, subtelomeric rearrangements, microdeletion or microduplication syndrome), monogenic, metabolic, or multifactorial alterations. Thanks to the development of high-resolution new techniques -comparative genomic hybridization (CGH) arrays, and multiplex ligation probe amplification (MLPA)- now we are able to detect microdeletions and microduplication all over the genome, which might be related with mental retardation.
The genetic causes of mental retardation are highly heterogeneous and complex. Nowadays and thanks to the new molecular techniques we are able to perform several studies, even though almost half of cases remain undiagnosed. In those undiagnosed cases with positive familial history a genetic counseling can be provided. However, in order to perform a prenatal or a preimplantational study a genetic diagnosis is required.
智力障碍是一种常见疾病，对患者本人、家庭及社会生活均有重大影响，在发达国家估计发病率为1%-3%。在导致智力障碍的病因中，约30%有遗传因素，15%由环境因素引起，其余病因不明。目的：报告智力障碍的遗传病因及用于诊断的新型分子技术。鉴于智力障碍病因对干预措施、预后、复发风险评估及预防的影响，确定其病因具有重要意义。
智力障碍的病因极其多样。遗传病因可分为染色体改变（非整倍体、亚端粒重排、微缺失或微重复综合征）、单基因、代谢或多因素改变。由于高分辨率新技术——比较基因组杂交（CGH）阵列和多重连接探针扩增（MLPA）的发展，我们现在能够检测全基因组的微缺失和微重复，这些可能与智力障碍有关。
智力障碍的遗传病因高度多样且复杂。如今，借助新型分子技术我们能够开展多项研究，尽管仍有近一半病例无法确诊。对于那些家族史呈阳性的未确诊病例，可提供遗传咨询。然而，要进行产前或植入前研究，则需要进行基因诊断。
