Background:

In 20% of neurodevelopmental disorders (NDD) and congenital abnormalities (CA) the cause would be a genomic imbalance detectable only by chromosomal microarrays (CMA).

Aim:

To analyze the results of CMA performed at the INTA Laboratory of Molecular Cytogenetics, during a period of four years in patients with NDD or CA.

Material and Methods:

Retrospective study that included all CMA reports of Chilean patients. Age, sex, clinical diagnosis and origin were analyzed, as well as the characteristics of the finding. The percentage of cases diagnosed by CMA was calculated considering all patients with pathogenic (PV) or probably pathogenic variants (VLP). Finally, we studied the association between patients' characteristics and a positive CMA outcome.

Results:

A total of 236 reports were analyzed. The median age was 5.41 (range 2.25-9.33) years, and 59% were men. Ninety chromosomal imbalances were found, which corresponded mainly to deletions (53.3%), with a median size of 1.662 (range 0.553-6.673) Megabases. The diagnostic rate of CMA in Chilean patients from all over the country was 19.2%. There was a close relationship between the patient's sex and the detection of VLP/VP (p = 0.034).

Conclusions:

Our diagnostic rate and the association between female sex and a higher percentage of diagnosed cases are concordant with other international studies. Therefore, CMA is a valid diagnostic tool in the Chilean population.