Detection of Hb Yulin [β13(A10)Ala→Val, HBB: c.41C>T] by Matrix-Assisted Laser Desorption Ionization-Time-of-Flight Mass Spectrometry

We report a rare hemoglobin (Hb) variant on the β-globin gene, which was detected in a female from Yulin City, Guangxi Autonomous Region, People's Republic of China (PRC), during routine thalassemia screening. The Hb variant remained unnoticed using capillary electrophoresis (CE) and high performance liquid chromatography (HPLC), while an additional peak was observed by matrix-assisted laser desorption ionization-time-of-flight (MALDI-TOF) mass spectrometry (MS). DNA sequencing revealed the GCC>GTC substitution at codon 13 on the β-globin gene, causing a substitution of alanine to valine. The mutation is only described in the ITHANET database but no Hb variant name and other information, so we named it Hb Yulin after the place of origin of the proband in this study. Hb Yulin is clinically silent and easily leads to misdiagnosis during hemoglobinopathies screening based on the common methods of HPLC and CE.

First Observation of HbM-Saskatoon at the Origin of Neonatal Cyanosis in a Tunisian Baby

Several causes are known to be at the origin of neonatal cyanosis among them methemoglobinemia is by inheritance of an hemoglobin (Hb) M variant. This is a rare condition never been reported in Tunisia so far. Here, we report a Tunisian newborn with refractory cyanosis since birth. As cardiac and respiratory diseases were ruled out, methemoglobinemia was suspected. Hematological parameters, concentration of methemoglobin, capillary electrophoresis, and amplification sequencing of the HBB gene were performed. Computational analysis was achieved by different in silico tools to investigate the mutation effect. The diagnosis was established by a raised MetHb, confirmed by the presence HbM-Saskatoon [Beta63 (E7) His>Tyr] by capillary electrophoresis and molecular analysis. The identified mutation occurred as a de novo mutation. In silico analysis confirmed the pathogenicity of the mutation. To our knowledge, this is the first time that this mutation has been reported in the Tunisian population. In view of its low incidence rate, clinicians might misdiagnose cyanosis caused by HbM, which can lead to inappropriate treatment and clinical complications. An up-to-date literature review of HbM disease is presented in this study.