Genetics and public health: the experience of a reference center for diagnosis of 22q11.2 deletion in Brazil and suggestions for implementing genetic testing.

Abstract

Considering the prevalence of 22q11.2 deletion syndrome (22q11.2 DS) of around 1:4,000 and of palatal abnormalities in 70% of the cases of 22q11.2 DS and taking into account the Brazilian health system and its current situation of medical genetic services, this study aims to contribute to establish strategies for genetic diagnosis. The access to genetic testing at 11 services was investigated and samples from 100 patients with palatal abnormalities and suspicion of 22q11.2 DS were sent to a reference center. Laboratorial techniques included karyotyping, fluorescence in situ hybridization (FISH), and multiplex ligation-dependent probe amplification. Costs were also calculated. Disparities among centers for genetic diagnosis were evident, with remarkable regional differences. Some of the obstacles encountered were difficulties for families to show up for medical appointments, complementary evaluations, and for the clinics to send the samples to the reference center. A conclusive diagnosis was reached for 38% of patients. Combination of karyotyping and FISH had better laboratorial cost-effectiveness. These results might represent the reality for the investigation of other genetic conditions. Clinical and laboratorial approaches herein presented could be adapted for use under different genetic conditions in the Brazilian health system, which has relatively limited financial and human resources. Suggestions for the rational implementation of genetic testing in developing countries are presented.