Alpha+ Thalassemia in Northwestern Tanzania: Molecular and Hematological Insights From Newborn Screening

This study aimed to determine the prevalence of alpha+ thalassemia and its hematological indices in a newborn population in Mwanza city, North-western Tanzania.

A cross-sectional study screened 803 newborns for alpha+ thalassemia that extracted DNA from dried blood spots using the Qiagen Mini Kit then analysed by multiplex PCR. Demographic data, anemia-related clinical information, and CBC parameters were collected at birth. Prevalence was determined by the proportion of newborns with the alpha+ thalassemia deletion. Fisher's Exact test assessed differences in demographic and clinical variables, while Student's t-tests and ANOVA evaluated hematological parameters. A P-value < 0.05 was considered statistically significant.

Alpha thalassemia was detected in 49.6% (398/803) of neonates, with 38.6% heterozygous and 11.0% homozygous deletions. Significant differences in erythrocyte indices were observed across groups. Hemoglobin (Hb) levels were lower in heterozygous (_α/αα) and homozygous (_α/_α) newborns (16.42±3.62 g/dl and 16.04±3.37 g/dl, respectively) compared to the αα/αα group (17.03±3.35 g/dl, p < 0.05). Mean Corpuscular Volume (MCV) was reduced in heterozygous (_α/αα) and homozygous (_α/_α) groups (99.23±9.12 μm³ and 94.75±9.88 μm³, respectively) compared to αα/αα (102.41±9.56 μm³, p < 0.0001). Mean Corpuscular Hemoglobin (MCH) followed a similar pattern, being lowest in the homozygous group (p ≤ 0.0001). Red Cell Distribution Width (RDW) was higher in homozygous (_α/_α) newborns (10.03±1.22) compared to heterozygous (_α/αα) (9.57±0.79, p < 0.001). Leucocyte counts were significantly higher in heterozygous (_α/αα) newborns (13.91±12.14) compared to homozygous (_α/_α) (12.60±7.91) and αα/αα groups (11.26±9.76, p = 0.001).

Alpha+ thalassemia is highly prevalent in North-western Tanzania and significantly affects blood indices. Neonatal screening is an effective tool for identifying affected children, especially in settings with high prevalence of a trait and low awareness of genetic inheritance.