Oman is a country with a population comprising of a wide range of ethnic groups, high rates of consanguinity and increased incidences of inter-cousin marriages. There is an increased prevalence of hemoglobinopathies which is of growing importance as knowledge of a population structure can be a unique aid in planning genetic services. The aim of this study was to establish neonatal cord blood screening in the Sultanate of Oman, in an effort to determine the prevalence of hemoglobinopathies by a costeffective method. High performance liquid chromatography [HPLC] is a powerful tool to screen newborns for hemoglobinopathies. Neonatal screening includes cord blood samples collection, screening, and follow up of all newborns with abnormal results. A total of 7837 consecutive cord blood samples were screened for presence of possible hemoglobinopathies by HPLC using Biorad Variant ?? program between April 2005 and March 2007. Complete blood counts [CBC] were also obtained on Cell Dyn 4000 automated blood cell counter. All samples were then processed to isolate and store mononuclear leukocytes for subsequent molecular diagnostics. The findings indicated a 47.07% incidence of ??thalassemia, based on low mean cell volume [MCV] and mean cell hemoglobin [MCH] on the CBC and significant amounts of Hb Barts on HPLC. The overall incidence of other hemoglobinopathies was 9.87%, with 5.47% incidence of sickle hemoglobin. On HPLC, D-window, E-window and C-window were present in 0.93%, 0.77% and 0.06% of the samples respectively. Since HPLC cannot diagnose beta thalassemia major at birth, in samples with HbA below 10%, the beta globin gene was directly sequenced including the promoter, all exons and introns in these samples. Amongst 206 (2.62%) samples sequenced, beta thalassemia trait was confirmed in 201 cases and 5 cases were found to be homozygous for beta thalassemia major. Additionally, direct sequencing of all abnormal samples with HbS [n=429], HbD [n=73], HbE [n=42], and HbC [n=5] was also performed on ABI Prism 3100 genetic analyzer to assign the correct genotype status to these subjects and use the same to validate the HPLC results. The significantly high incidence of hemoglobinopathies in newborns in the Sultanate of Oman emphasizes the value of neonatal cord blood screening to be implemented as the first step in the national strategy towards total management of hemoglobinopathies including early diagnosis, comprehensive clinical care and counseling of the affected families. The results of this large study wound indicate that using HPLC [<2 USD/sample] is a cost effective method. Moreover, prescreening of both parents and selecting only samples of neonatal cord blood from newborns with either parent having an underlying genetic trait for hemoglobinopathy would result in the a huge cost saving to the tune of over 90% as compared to universal neonatal cord blood screening and can be recommended as a highly cost-effective method targeted to screen only the abnormal samples.
Author(s): Al-Kindi S., Pathare A.V., Al-Madhani A., Al-Zadjali S., Krishnamoorthy R.