Molecular Diagnosis and Stability Testing of Hemoglobin Phnom Penh [ <i>HBA1</i> : C.353_355dup (p.Phe118_Thr119insIle)] – The First Northern Thai Case

Hemoglobin (Hb) Phnom Penh is a rare Hb variant of non-clinical significance caused by a duplication of TCA within exon 3 of the human <i>HBA1</i> gene, resulting in the insertion of isoleucine [c.353_355dup (p.Phe118_Thr119insIle)]. This variant can interfere with glycated Hb analysis and has been identified in several Asian populations, including Cambodian, Chinese, northeastern Thai, and Taiwanese individuals. In this study, we identified a northern Thai man with Hb Phnom Penh. The proband was a heterozygote and asymptomatic. The inheritance of Hb Phnom Penh was suspected based on his abnormal Hb pattern observed through high-performance liquid chromatography and confirmed by Sanger sequencing. Additionally, molecular analysis revealed that Hb Phnom Penh exhibits greater instability compared to HbE. Our findings report, for the first time, the presence of Hb Phnom Penh in northern Thailand and its instability, suggesting the heterogeneity of this Hb variant in Thailand and providing further insights into its basic characteristics.