Adriana Rosolio Costa Sabbag¹, Bruno Garcia Rocha¹, Lucimar Retto da Silva de Avó², Carla Maria Ramos Germano^{1, 2}, Euclides Matheucci Junior¹, Débora Gusmão Melo^{1, 2,}

Unexplained intellectual disability is a clinical situation in which molecular diagnostic techniques should be indicated. The diagnostic yield of Multiplex Ligation-dependent Probe Amplification (MLPA) in a cohort of patients with intellectual disability and dysmorphic features was investigated to identify microdeletion syndromes. We aimed to provide an example of the utilization of MLPA method in the medical care routine that can be useful for planning the inclusion of molecular genetic testing in the Brazilian public health care system. This study was based on 57 patients who had different degrees of intellectual disability with etiology not determined. All patients had normal brain CT scan or MRI and normal karyotype, and patients with environmental damage history were not included. Two of the 57 patients were referred to molecular genetic testing as they were clinically diagnosed as having Williams syndrome. MLPA test costs were calculated (human resources and equipment costs were not included in the calculation). MLPA revealed chromosomal imbalance in 4 out of 57 patients (7%). These imbalances were associated with well-described microdeletion syndromes: 3 patients had Williams syndrome (1 without clinical diagnosis) and 1 patient had 22q11.21 deletion syndrome. The MLPA analysis cost per individual, considering DNA extraction and laboratory reagents, was US$66.40. In this study, MLPA confirmed its value as a promising technique as it has adequate feasible characteristics to identify microdeletion syndromes in patients who had unexplained intellectual disability. This work suggests that MLPA can be a viable alternative to implement molecular genetic testing in the Brazilian public health care system, considering its cost-effectiveness.

biomedical technology assessment, molecular diagnostic techniques, genetic testing, genetic services, intellectual disability, public health, brazil