Leslie Holley

The influence of uridine diphosphate glucuronosyl transferase 1A promoter polymorphisms, βS‐globin gene haplotype, co‐inherited α‐thalassemia trait and Hb F on steady‐state serum bilirubin levels in sickle cell anemia

Abstract:  Purpose: Homozygosity for the (AT)7 allele of uridine diphosphate glucuronosyl transferase 1A (UGT1A1) gene polymorphism is associated with increased bilirubin levels in sickle cell anemia (SCA). In the present study, in addition to UGT1A1 promoter genotype, serum bilirubin level was related to other genetic modifiers –βS‐globin gene haplotype, Hb F, co‐inherited α‐thal trait, age and gender. Methods: The patients were randomly selected from the sickle cell clinic, Medical College of Georgia. UGT1A1 promoter polymorphisms were determined using automated sequencing. Other investigations were with standard techniques. Results: There were 67 SCA patients (41 males and 26 females), aged 2–44 yr (mean of 20.6 ± 10.7). Ten (14.9%) patients were homozygous for the (AT)6 UGT1A1 allele, 35 (52.2%) were heterozygous for (AT)6 and (AT)7 alleles while 22 (32.8%) were homozygous for (AT)7. Serum bilirubin was significantly higher in the homozygous (AT)7 group (3.7 ± 1.5, 3.8 ± 2.3 and 5.6 ± 2.4 mg/dL, respectively). It was also significantly higher in males than females and in patients aged >10 yr. There was a significant negative linear correlation (r = −0.304, P = 0.016) of serum bilirubin with Hb F. The β‐globin haplotype and co‐existing α‐thal trait did not have any significant influence on serum bilirubin levels. Patients on hydroxyurea were older, had lower Hb F, but higher mean serum bilirubin. The latter also was signifcantly higher among those with UGT1A1 (AT)7 homozygosity. Conclusions: Apart from UGT1A1 (AT)7 homozygosity, Hb F, age and gender are the other factors that significantly influence serum bilirubin level in SCA.

Interaction of Sickle Cell Trait with Hereditary Spherocytosis: Splenic Infarcts and Sequestration

The association of sickle cell trait (SCT) and hereditary spherocytosis (HS) has been reported in only 18 patients. Three of these 18 patients experienced splenic infarct or acute splenic sequestration. We report here a 46-year-old African-American male, the oldest reported case to date, who experienced episodes of hemolysis and severe left upper quadrant pain for the past 26 years. The patient had compensated hemolysis with splenomegaly. A CT scan of the abdomen revealed a large infarct in the spleen. The diagnosis of SCT was confirmed with isoelectric focusing, cation exchange and reverse-phase HPLC. The presence of a silent, interacting globin variant as the cause of hemolysis and sickling in the spleen was ruled out by sequencing of the α1-, α2- and β-globin genes. The diagnosis of HS was established by an osmotic fragility test. The interaction of HS and SCT leads to RBC dehydration with increased MCHC and intracellular Hb S concentration presumably favoring intrasplenic sickling and resultant splenic infarcts and sequestration as seen in this case.

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.

Molecular characterization of Hb D-Ibadan [β87(F3)Thr→Lys] in combination with Hb S [β6(A3)Glu→Val] and with β+-thalassemia: Report of two cases

Hb D-Ibadan [β87(F3)Thr→Lys] is a common variant in the Nigerian population, which has been reported in association with Hb S [β6(A3)Glu→Val] and with β-thalassemia. Unlike the Hb S/Hb D-Los Angeles [β121(GH4)Glu→Gln] combination, compound heterozygosity for Hb D-Ibadan and Hb S does not result in a sickling disorder. We report the first case of a combination of Hb D-Ibadan with β+-thalassemia, and the first observation of Hb S/Hb D-Ibadan in the African-American population. In both cases, the characterization of Hb D-Ibadan was achieved by sequencing of the genomic DNA. Although protein based methods such as isoelectrofocusing and high performance liquid chromatography may suggest that the “D-like” variant is different from Hb D-Los Angeles, the definitive identification of the variant by structural analysis or molecular genetic methods should be undertaken, particularly in newborn screening programs when the variant is found in combination with Hb S.

Rare occurrence of Hb Lepore-Baltimore in African Americans: molecular characteristics and variations of Hb Lepores

Hb Lepore is the hybrid hemoglobin (Hb) composed of two α-globin chains and two δβ hybrid chains and is associated with the clinical findings of thalassemia minor in its heterozygous form. Hb Lepore can be found in many ethnic groups, commonly in southern European countries, but rarely in African Americans. The first Hb Lepore case in an African-American individual was named Hb Lepore-The Bronx (Hb Lepore-Boston). Hb Lepore-Washington-Boston and Hb Lepore-Baltimore with a breakpoint of (δ50Ser/β86Ala) were later reported. In this paper, we describe an Hb Lepore-Baltimore (δ68Leu/β84Thr) δβ-fusion gene with a different breakpoint detected for the first time in an African-American female. We have used state-of-the-art technology, combining protein- and DNA-based methods, in the analysis of the hybrid hemoglobin and discuss its molecular characteristics.

Two new hemoglobin variants: Hb Sinai-Greenspring [β34(B16) Val→Ile, GTC > ATC] and Hb Sinai-Bel Air [β53(D4)Ala→Asp, GCT > GAT]

Neonatal screening for hemoglobinopathies occasionally results in the detection of novel hemoglobin (Hb) variants. Two heterozygous infants were found with different β chain mutations, neither of which produced obvious clinical or laboratory abnormalities on routine examinations. The variants were characterized by cation exchange high performance liquid chromatography (HPLC), reversed phase HPLC, and sequencing of amplified β-globin genes. Functional studies could not be performed at this time.