Cytogenomic investigation in patients with congenital anomalies and mental retardation

Abstract

Chromosomal rearrangements represent a major cause of mental retardation and congenital malformations. The investigation of these imbalances is usually made by karyotype, which is relatively simple and cheap. However, considering its low resolution, a large proportion of patients, even with a clinical phenotype suggestive of cytogenetic alterations, remain without etiology recognition. Recently, the genomic array was proposed to be used as the first clinical diagnostic test due to its high resolution. However, this exam is too expensive to be used in routine diagnosis in developing countries. An alternative method for cytogenetic alterations screening in patients with normal karyotype is the MLPA (Multiplex Ligation-dependent Probe Amplification) technique, an inexpensive tool based on polymerase chain reaction (PCR) with different probes simultaneously. Among them, the subtelomeric probes have been used because they are able to identify subtelomeric region imbalances, which are frequently involved with pathogenic structural alterations. The purpose of this study is to establish the cytogenetic diagnosis of patients who have suggestive features of chromosomal imbalances using MLPA and microarray techniques. The characterization of the region involved in imbalances and the comparison with other reports in the literature will allow contributing to a better phenotypic map delimitation of the involved chromosomes. (AU)