[Diagnosis of chromosomal abnormalities by array CGH in constitutional pathology: the end of the first-line karyotype].

Today, the array CGH has supplanted the karyotype for the global study of the genome with a resolution from 10 to 500 times better and with providing access to the genes content of the chromosomal rearrangement. The study of patients with intellectual disabilities and/or congenital malformations allowed to detect thanks to this technique 10 to 15% of abnormalities not visible on the karyotype. In addition, its use extended to other indications revealed anomalies associated with neuropsychiatric diseases (such as autism, schizophrenia, bipolar disorder or isolated epilepsy) and cardiac, bone, kidney or other isolated defects. The analysis of genes in the unbalanced chromosome segment to establish the causal link between the genomic imbalance identified and the pathology observed is at the core of the cytogeneticist's work. The array CGH freeing a morphological analysis of chromosomes of the karyotype in contrast, offers the advantage of being fully automated allowing improved reliability and reproducibility of the results and a study of more patients. Today, it has become the first-line test to explore the genome of many patients.