TRIAGEM NEONATAL DE IMUNODEFICIÊNCIAS GRAVES COMBINADAS POR MEIO DE TRECS E KRECS: SEGUNDO ESTUDO PILOTO NO BRASIL

Marilia Pyles P Kanegae, Lucila Akune Barreiros, Jusley Lira Sousa, Marco Antônio S Brito, Edgar Borges de Oliveira, Lara Pereira Soares, Juliana Themudo L Mazzucchelli, Débora Quiorato Fernandes, Sonia Marchezi Hadachi, Silvia Maia Holanda, Flavia Alice T M Guimarães, Maura Aparecida P V V Boacnin, Marley Aparecida L Pereira, Joaquina Maria C Bueno, Anete Sevciovic Grumach, Regina Sumiko W Di Gesu, Amélia Miyashiro N Dos Santos, Newton Bellesi, Beatriz T Costa-Carvalho, Antonio Condino-Neto

To validate the quantification of T-cell receptor excision circles (TRECs) and kappa-deleting recombination excision circles (KRECs) by real-time polymerase chain reaction (qRT-PCR) for newborn screening of primary immunodeficiencies with defects in T and/or B cells in Brazil. Blood samples from newborns and controls were collected on filter paper. DNA was extracted and TRECs, and KRECs were quantified by a duplex real-time PCR. The cutoff values were determined by receiver operating characteristic curve analysis using SPSS software (IBM®, Armonk, NY, USA). Around 6,881 samples from newborns were collected and TRECs and KRECs were quantified. The TRECs values ranged between 1 and 1,006 TRECs/µL, with mean and median of 160 and 139 TRECs/µL, respectively. Three samples from patients with severe combined immunodeficiency (SCID) showed TRECs below 4/µL and a patient with DiGeorge syndrome showed undetectable TRECs. KRECs values ranged from 10 to 1,097 KRECs/µL, with mean and median of 130 and 108 KRECs/µL. Four patients with agammaglobulinemia had results below 4 KRECs/µL. The cutoff values were 15 TRECs/µL and 14 KRECs/µL and were established according to the receiver operating characteristic curve analysis, with 100% sensitivity for SCID and agammaglobulinemia detection, respectively. Quantification of TRECs and KRECs was able to diagnose children with T- and/or B-cell lymphopenia in our study, which validated the technique in Brazil and enabled us to implement the newborn screening program for SCID and agammaglobulinemia.