The inclusion of ADA-SCID in expanded newborn screening by tandem mass spectrometry.
Severe combined immunodeficiency due to adenosine-deaminase defect (ADA-SCID) is usually deadly in childhood because of severe recurrent infections. When clinical diagnosis is done, permanent damages due to infections or metabolite accumulation are often present. Gene therapy, bone marrow transplantation or enzyme replacement therapy may be effective if started early. The aim of this study was to set-up a robust method suitable for screening with a minimized preparation process and with inexpensive running costs, for diagnosing ADA-SCID by tandem mass spectrometry. ADA-SCID satisfies all the criteria for inclusion in a newborn screening program. We describe a protocol revised to incorporate adenosine and 2-deoxyadenosine testing into an expanded newborn screening program. We assessed the effectiveness of this approach testing dried blood spots from 4 genetically confirmed early-onset and 5 delayed-onset ADA-SCID patients. Reference values were established on 50,000 healthy newborns (deoxyadenosine <0.09μmol/L, adenosine <1.61μmol/L). We also developed a second tier test to distinguish true positives from false positives and improve the positive predictive value of an initial abnormal result. In the first 18 months, the pilot project has identified a newborn with a genetically confirmed defect in adenosine deaminase (ADA) gene. The results show that the method having great simplicity, low cost and low process preparations can be fully applicable to a mass screening program.
Newborn Screening, Biochemistry and Pharmacology Laboratories, Clinic of Pediatric Neurology, Meyer University Children's Hospital, Florence, Italy; Department of Neurosciences, Psychology, Pharmacology and Child Health, University of Florence, Italy. Electronic address: g.lamarca@meyer.it.
Giancarlo
G
la Marca
Elisa
E
Giocaliere
Sabrina
S
Malvagia
Silvia
S
Funghini
Daniela
D
Ombrone
Maria Luisa
ML
Della Bona
Clementina
C
Canessa
Francesca
F
Lippi
Francesca
F
Romano
Renzo
R
Guerrini
Massimo
M
Resti
Chiara
C
Azzari
D000243:Adenosine Deaminase / Q000097:blood*; D002138:Calibration; D059788:Dried Blood Spot Testing; D006801:Humans; D007231:Infant, Newborn; D015997:Neonatal Screening / Q000379:methods*; D010865:Pilot Projects; D011237:Predictive Value of Tests; D012016:Reference Values; D015203:Reproducibility of Results; D012189:Retrospective Studies; D016511:Severe Combined Immunodeficiency / Q000097:blood* / Q000175:diagnosis; D053719:Tandem Mass Spectrometry
D000243:Adenosine Deaminase
2-deoxyadenosine; ADA; ADA-SCID; Adenosine-deaminase defect; Ado; DBS; ERT; Expanded newborn screening; HPLC; LC–MS/MS; LLOQ; LOD; MRM; MS; RT; SCID; SUAC; Second tier test; T-cell receptor excision circles; TRECs; adenosine; adenosine deaminase; dAdo; dried blood spot; enzyme replacement therapy; high-performance liquid chromatography; limit of detection; liquid chromatography/tandem mass spectrometry; lower limit of quantitation; mass spectrometry; multiple reaction monitoring; room temperature; severe combined immunodeficiency; severe combined immunodeficiency due to adenosine-deaminase defect; succinylacetone