THE USE OF HPLC AS A TOOL FOR NEONATAL CORD BLOOD SCREENING OF HAEMOGLOBINOPATHY - A VALIDATION STUDY

Abstract

Background: Newborn cord blood screening identifies infants with underlying haemoglobinopathies before they develop the characteristic symptoms or sequelae. Aims: This study was performed to validate the interpretation high-performance chromatography (HPLC) along with complete blood count (CBC) results as a tool for universal neonatal screening of hemoglobin disorders in Oman. Methods: HPLC and CBC data on subjects who participated in the National Neonatal screening program at birth were obtained from archival records. The results recorded at birth were compared with a second study performed on the same subjects, after approval from the local medical research and ethics committee.Results: Only 290 subjects from amongst the original cohort of 3740 newborns could be recalled between April 2010 to March 2011, to repeat HPLC and CBC, as well as perform confirmatory DNA studies, wherever necessary. All these subjects had been documented to show an initial abnormal result. 31 cases who had no HbA at birth on HPLC were confirmed as either homozygous β-thalassaemia major (n=5 subjects) or homozygous sickle cell anemia (n=26 subjects) by appropriate DNA analysis. Additionally, amongst 151 subjects, 72 subjects were studied in the initial study by Hb Bart’s quantitation using aalpha thalassaemia short program at birth. In this cohort, 42 subjects with Hb Bart’s >1% at birth could be confirmed as having either deletional or non-deletional thalassaemia by GAP PCR studies. No case of HbH was detected in this cohort. Further, carrier status for structural hemoglobin variants (HbS, HbC, HbD, HbE) (n=67) and beta thalassaemia allele with low HbA at birth (n=29 out of 41) were confirmed by relevant molecular studies.Conclusions: The study validated the earlier observation by 100% concordance with results of CBC and HPLC. Presence of Hb Bart’s at birth does not always mean the presence of alpha thalassemia, as subjects with Hb Bart’s was below 1% by quantitation, were shown to be normal by molecular studies. Key Words: Neonatal, screening, HPLC validation, haemoglobinopathy, sickle cell disease, thalassaemia