RESUMEN
BACKGROUND/PURPOSE: In order to know the true incidence of severe combined immunodeficiency (SCID) in a Chinese population, we conducted and implemented SCID newborn screening in Taiwan. METHODS: Between May 1, 2010 and December 31, 2011, the National Taiwan University Hospital Newborn Screening Center screened all newborns for T-cell lymphopenia by measuring the copy number of T-cell receptor excision circles (TRECs) and RNase P. Newborns with low TREC values were subjected to complete blood cell counts and flow cytometry. RESULTS: A total of 106,391 newborns were screened using the TREC assay over a period of 19 months. Five newborns were immediately referred for confirmatory tests, including two SCID patients and two patients with persistent T-cell lymphopenia; a third SCID patient was found 2 months after the study period. All three SCID cases received stem cell transplantation at the age of 2-5 months. We also identified five cases of 22q11.2 microdeletion syndrome. During this period, two SCID patients from among the unscreened newborns were reported, and they died at ages 3 months and 4 months, respectively. CONCLUSION: Newborn screening to measure the number of TREC copies successfully identifies newborns with T-cell lymphopenia, 22q11.2 microdeletion syndrome, and other high-risk conditions. Taken together, the incidence of T-cell lymphopenia in apparently healthy newborns is more than 1 in 11,821, and further attention to their immune functions is warranted.
Asunto(s)
Linfopenia/epidemiología , Tamizaje Neonatal , Inmunodeficiencia Combinada Grave/epidemiología , Pueblo Asiatico , Femenino , Humanos , Incidencia , Lactante , Recién Nacido , Recuento de Linfocitos , Masculino , Taiwán/epidemiologíaRESUMEN
BACKGROUND/PURPOSE: Glutaric aciduria type 1 (GA1) is an inborn error of lysine and tryptophan metabolism. There is a lack of initial diagnostic signs of the disease, but late treatment often results in severe neurologic impairment. In this study, we analyzed the results of screening for GA1 in a Chinese population. METHODS: Dry blood spots were obtained at about 3 days of age from 357,307 newborns and tested for elevation of glutaryl (C5DC)-carnitine by tandem mass spectroscopy. A second sample of blood spots was required from those cases with abnormal elevation of C5DC-carnitine (higher than the cut-off value) (recall). If the results remained abnormal, those cases were referred for confirmation of the diagnosis and treatment. RESULTS: Between August 2001 and February 2005, there were 40 cases with C5DC-carnitine more than 0.13 microM (the cut-off value), from whom a second sample of blood spots was obtained (recall rate, 0.02%); two cases were confirmed to be affected by GA1. Because of the low positive prediction rate using this cut-off value, we elevated the cut-off value slightly. Between February 2005 and August 2006, there were eight cases with C5DC-carnitine more than 0.22 microM from whom a second sample of blood spots was obtained (recall rate, 0.01%); three cases were confirmed to be affected by GA1. All five cases with persistent elevation of C5DC-carnitine were referred and diagnosis was confirmed in each, giving an incidence of 1 in 71,461 newborns. There were no false negatives. Magnetic resonance imaging studies obtained from four cases showed frontotemporal atrophy at the time of diagnosis. Two cases were followed for over 1 year, and under treatment with dietary control and carnitine supplementation, both had normal development and neither exhibited a frank episode of encephalopathic crisis. CONCLUSION: With properly established cut-offs, GA1 can be successfully screened for in populations with a low incidence of the disease. Early treatment is likely to improve the outcome of cases discovered by screening.