Cd 41/42 (-TTCT), IVS 1-5 (G-C), IVS 1-1 (G-T), and HbE are the most common β-globin defects among Malaysian Malays, and compound heterozygous states of the four mutations are commonly encountered. Here, we described the hematologic and DNA characterizations of our first-time encountered compound heterozygous state of β° Cd 41/42 (-TTCT) and a mild β+ TATA box mutation, -30 (T>C), in a Malay patient leading to β-thalassemia major. At the age of 2, she presented with symptomatic anemia, hepatosplenomegaly, and was put on a β- thalassemia major treatment regime. Now, at the age of 6, she was found to be autistic, a slow learner with social interaction problems, and she is under a psychiatric follow up for autism. Inevitably, the detection of β-globin defects among Malaysians must include comprehensive molecular analyses for an accurate assessment of emerging and rare mutations, as well as modifier genes affecting disease severity.