Lina Zhuang

Neonatal Cyanosis Due to a Novel Fetal Hemoglobin: Hb F-Circleville [Gγ63(E7)His→Leu, CAT>CTT]

Neonatal cyanosis can result from a multitude of acquired and inherited causes. Cyanosis resulting from fetal M hemoglobin (Hb) variants is very rare. Only two Gγ variants causing methemoglobinemia and cyanosis in the newborn have been reported to date. Here we describe a novel fetal Hb variant, Hb F-Circleville [Gγ63(E7)His→Leu], associated with methemoglobinemia and cyanosis in the newborn. The patients sister also had neonatal cyanosis at birth.

Hb M Dothan [β 25/26 (B7/B8)/(GGT/GAG→GAG//Gly/Glu→Glu]; a new mechanism of unstable methemoglobin variant and molecular characteristics

A new unstable beta globin chain variant associated with methemoglobin (Met-Hb) phenotype was found in a Caucasian infant. Molecular analysis of the beta globin gene using polymerase chain reaction (PCR) amplification and sequencing led to the detection of a new in frame deletion in exon-1. Direct sequencing of the PCR product revealed a 3 bp deletion (-GTG) between codons 25/26, which resulted in the loss of a single amino acid (-Gly). We propose that this newly discovered unstable M-hemoglobin (M-Hb) variant, named Hb Dothan [GGT/GAG-->GAG//Gly/Glu-->Glu], is caused by a shift in the amino acid sequence and altered packing of the B and E helices during beta globin synthesis, and also changes the orientation of the critical proximal and distal histidine in the F and E helices respectively. Phenotype/Genotype features and molecular characteristics of this new beta chain are presented in this communication.

Thalassemia-like phenotype in a novel complex hemoglobinopathy with α, β, δ globin chain abnormalities.

The occurrence of multiple abnormalities of &agr;, &bgr;, &dgr;, and &ggr; globin genes may lead to unusual and complex phenotypes when they arise simultaneously in the same individual. Here, we report the findings of an African American boy who coinherited 3 heterozygous globin gene abnormalities: the unstable &bgr;-globin chain variant; hemoglobin (Hb) Showa-Yakushiji [&bgr;110(G12) Leu→Pro], the &dgr;-globin chain variant; HbB2 [&dgr;16(A13) Gly→Arg] and &agr;+-thalassemia (&agr;+-thal); (&agr;-3.7/&agr;&agr;). Hb Showa-Yakushiji had been previously described in Japanese, Indian, and European populations. We report its first occurrence in a child of African ancestry who presented with anemia not responsive to iron and an incomplete &bgr;-thalassemia minor phenotype. Although the clinical and laboratory features of Hb Showa-Yakushiji mimic those of a &bgr;-thalassemia, the coinheritance of the &dgr;-globin chain variant Hb B2 suppressed the relative increase in Hb A2 usually observed in heterozygotes for the Hb Showa-Yakushiji mutation. Protein-based methods detected only a trace amount of HbB2 and failed to reveal presence of Hb Showa-Yakushiji and &agr;+-thal. The latter were only identified through DNA analyses. The diagnostic difficulties, molecular characteristics, and genotype/phenotype correlations of this novel complex hemoglobinopathy syndrome are reviewed.

Hemoglobin F Only Syndrome at Birth: A Case of Maternal HbA2' Complicating the Diagnosis of β-Thalassemia.

An asymptomatic infant of Ghanaian descent had hemoglobin F only detected on newborn screening. &bgr;-globin gene sequencing identified the intervening sequence (IVS)-II-849 (A→G) mutation with no normal &bgr;-globin gene. &bgr;-globin/&dgr;-globin gene sequencing showed that both parents were heterozygous for the IVS-II-849 (A→G) mutation. The mother was heterozygous for the HbA2’ &dgr;-globin mutation (&dgr;16 (A13) Gly→Arg), thus &bgr;-thalassemia trait was unrecognized due to coinheritance of HbA2’. The infant developed anemia, splenomegaly, and began transfusion therapy by the age 6 of months. This is the first report of &bgr;-thalassemia major with homozygous IVS-II-849 (A→G) mutations. This case highlights the importance of &dgr;-globin gene mutations in prenatal testing.

Two new γ chain variants: Hb F-Augusta GA [Gγ59(E3)Lys→Arg; HBG2: C.179A>G] and Hb F-Port Royal-II [Aγ125(H3)Glu→Ala; HBG1: C.377A>C]

Abstract The total number of hemoglobin (Hb) variants so far reported to the HbVar database is 1598 (April 9 2014) and 130 of them are fetal Hb variants. Fetal Hb are categorized as two different subunits, Gγ- and Aγ-globin chains, and γ chain variants can be observed in both subunits. There are 72 Gγ- and 58 Aγ-globin chain variants. Most of them are clinically silent and detected during newborn screening programs in the USA and outside the USA. In this report, we discuss the molecular characteristics and diagnostic difficulties of two new γ-globin chain variants found in an African American baby with no clinical symptoms. One is a new Gγ-globin chain variant, Hb F-Augusta GA [Gγ59(E3)Lys → Arg; HBG2: c.179A > G] and the other one is Hb F-Port Royal-II [Aγ125(H3)Glu → Ala; HBG1: c.377A > C].

Two New Hemoglobin Variants: Hb Tallahassee [α3(A1)Ser→Tyr; HBA2: c.11C>A] and Hb Madison-NC [β119(GH2)Gly→Ser; HBB: c.358G>A]

Abstract Of the 1570 reported hemoglobin (Hb) variants detected to date, 390 are α2-globin chain (some variants have yet to be identified by DNA analyses and are therefore presumed) and 827 are the result of mutations of the β-globin chain. Due to their location on the Hb structure, only a minority of these variants result in a clinical phenotype; most are silent and are detected during routine surveillance, are found incidentally during other disease-related investigations or following newborn screening programs. In this report we discuss phenotype/genotype and molecular characteristics of two new Hb variants, both of which were clinically silent. One is an α2-globin chain variant located at codon 3 [α3(A1)Ser→Tyr; HBA2: c.11C > A] named Hb Tallahassee and the other is a β-globin chain variant located at codon 119 [β119(GH2)Gly→Ser; HBB: c.358G > A] called Hb Madison-NC.

Nondeletional α-Thalassemia (α2- IVS-1-116, A>G HBA2): An α2 Gene Point Mutation Detected in an African-American Female for the First Time

α-thalassemia to the T.H.J. Huisman Hemoglobinopathy/ Genetic Testing Laboratory here at the Medical College of Georgia/Georgia Regents University, Augusta, Ga., USA. A hemolysate, prepared and first analyzed on the isoelectrofocusing gel, confirmed Hb A and Hb A2. Hb components were quantitated by using a cation-exchange, highperformance liquid-chromatography (HPLC) column (Synchropak CM-300, CCM10325, 0.46 × 25 cm dimensions, 7-μm particle size; Eprogen, Darien, Ill., USA). Results revealed Hb A (98%), Hb A2 (2%, on the lower end of normal) and HbF (<0.5%) levels. Globin chain analyses performed using a reversed-phase HPLC column (Supelco-5, 0.46 × 25 cm dimensions, 5-μm particle size; Discovery, Sigma-Aldrich, Bellefonte, Pa., USA) showed the presence of α-, βAand δA2-globin chains. No abnormalities were detected. The detailed method used here has been reported previously [2, 3] . Genetic testing was performed to characterize the α-globin gene deletion and mutations, using conventional methods. In order to screen for deletional α-thalassemia-2, a gap PCR method was used as described previously. Sequencing of selectively amplified PCR products of α1and α2-globin genes was performed according to a method reported previously [4] . The patient was screened for common type α-thalassemia-2 (–3.7 deletion) and was found to be negative. As she did We describe a case of a nondeletional α-thalassemia mutation found in an African-American individual [1] . A nondeletional α2-globin gene mutation (α2-IVS-1–116, A>G) was detected in a 68-year-old, African-American female for the first time. She was examined in September 2009 here at the Medical College of Georgia by a Hematology member, who suspected her of having a mild α-thalassemia phenotype. A year earlier, she had undergone a successful hiatoplasty, a pyloroplasty and a highly selective vagotomy for pyloric stenosis and refractory gastroesophageal reflux disease. She was noted to have a microcytic anemia that did not resolve after successful surgery. Her abdominal symptoms improved but she continued to complain of fatigue. Her hematological analyses revealed: hemoglobin (Hb) 8.6 g/dl, red blood cell count 3.3 × 10 12 /l, mean corpuscular volume 78.8 fl, hematocrit 26.2%, mean corpuscular Hb 25.8 pg, mean cellular Hb concentration 32.8 g/dl and red blood cell distribution width 22.5%. Her serum iron level was 108 μg/dl, total iron-binding capacity level 303 μg/dl and ferritin 266.3 ng/ml. These values excluded the possibility of iron deficiency. A Hb electrophoresis showed Hb A and Hb A2 bands which were normal. A deletional α-thalassemia-2 (–3.7 deletion, a common type in the African-American population) was suspected. Her blood, collected in EDTA (anticoagulant), was sent for definitive identification of Received: August 28, 2013 Accepted: September 1, 2013 Published online: December 13, 2013

Hb Fulton-Georgia [α20(B1)His→Pro; HBA1: c.62A>C]: a new α-globin variant coinherited with α-thalassemia-2 (3.7 kb deletion) and Hb SC disease.

We report a novel hemoglobin (Hb) variant that we named Hb Fulton-Georgia, caused by a point mutation in exon 1/codon 20 of the α-globin gene [α20(B1)His→Pro; HBA1: c.62A>C]. This α chain variant was identified in an adult African-American female with Hb SC disease who was also heterozygous for the α-thalassemia-2 (α-thal-2) (3.7 kb deletion or αα/–α3.7). The Hb Fulton-Georgia mutation was located on the intact α1-globin gene not involved by α-thal-2. Molecular models indicated that the α20 residue of Hb Fulton-Georgia was the first amino acid of the B helix, and was not involved in α1/β1 or α1/β2 contacts in Hb S [β6(A3)Glu→Val; HBB: c.20A>T] or Hb C [β6(A3)Glu→Lys; HBB: c.19G>A] tetramers. Furthermore, the histidine→proline substitution at α20 did not disrupt the helical structure. High performance liquid chromatography (HPLC) detected Hb Fulton-Georgia in 16.0% of total Hb, consistent with inheritance on the α1 gene. Coinheritance of Hb Fulton-Georgia, heterozygous α-thal-2 and Hb SC disease was associated with a mild phenotype, consisting of microcytosis and anisocytosis, but no anemia or other hematological abnormality.