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Cytogenomic investigation in patients with congenital anomalies and mental retardation

Grant number: 13/10540-2
Support type:Scholarships in Brazil - Scientific Initiation
Effective date (Start): July 01, 2013
Effective date (End): December 31, 2013
Field of knowledge:Biological Sciences - Genetics
Principal Investigator:Maria Isabel de Souza Aranha Melaragno
Grantee:Hélio Rodrigues de Oliveira Júnior
Home Institution: Escola Paulista de Medicina (EPM). Universidade Federal de São Paulo (UNIFESP). Campus São Paulo. São Paulo , SP, Brazil


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 clinical phenotype suggestive of cytogenomic alterations, remain without etiology recognition. Recently, 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 cytogenomic 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 cytogenomic 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.