Haematological Profile of Hb Adana Among High School Students in Northeast of Peninsular, Malaysia

Abstract

Hb Adana is a non-deletional α-thalassaemia variant, due to mutations in α1- or α2-globin codon 59 (αCD59) that produce unstable α-globin. Clinical appearance can range from silent carrier to blood transfusion reliance, hepatosplenomegaly, skeletal deformities, and spinal cord compression. Despite the importance of Hb Adana inheritance, this Hb variant is challenging to study since molecular tests are scarce and routine diagnosis can be missed. This study explored the distribution of Hb Adana among local high school students and evaluate the hematological parameters and haemoglobin analysis of Hb Adana in this region of Malaysia. This retrospective study included 13,721 blood samples from high school students enrolled in Malaysia's National Thalassaemia Screening Program at Hospital Raja Perempuan Zainab II (HRPZ II). Multiplex Gap PCR was used to detect deletional α-thalassaemia. Common non-deletional α-thalassaemia was detected using multiplex ARMS PCR. Evaluable data were retrieved from the HRPZ II database. Results: A total of 2327 subjects exhibited common deletional (n=1037, 44.6%) and non-deletional (n=1290, 55.4%) α-thalassaemia. Hb Constant Spring was the most frequent non-deletional α-thalassaemia. Thirty-one participants (1.33%) had αCD59α/αα and one (0.04%) had αCD59α/-α3.7. The 32 Hb Adana subjects were 87.5% Malay, and 12.5% Orang Asli. Additionally, seven cases of HbE/Hb Adana were discovered. The haemoglobin level in heterozygous Hb Adana ranged from mild anaemia to normal, 95.0 g/L to 153.0 g/L. The MCV and MCH were approximately 73 fL and 23 pg, respectively. Conclusions: We have denoted the distribution of alpha thalassaemia mutation patterns among high school students in Kelantan, Northeast Peninsular of Malaysia. Our observation showed Hb Adana was rarely uncommon in our region and the co-inheritance with an α-gene deletion generates α+-thalassaemia; with HbE, α0-thalassaemia. All heterozygous Hb Adana exhibited low MCVs and MCHs.