Hb Stanleyville-II [α78(EF7)Asn→Lys (α2); HbA2: c.237C>A]: Incidence of 1:11,500 in a Newborn Screening Program in Brazil

Abstract

Almost 3 million babies were tested in a newborn screening program in Minas Gerais, Brazil (1998–2008); 128 who have S-like hemoglobins (Hbs) were tested for the β^S allele and 112 were identified through polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) or sequencing. Hb Stanleyville-II [α78(EF7)Asn→Lys (α2); HbA2: c.237C>A] was present in 96 children (85.7%), two in a homozygous state and 94 in a heterozygous state. Its estimated prevalence was 1:11,500. Hbs Hasharon [α47(CE5)Asp→His, GAC>CAC (α2)], Ottawa [α15(A13)Gly→Arg (GGT>CGT) (α2 or α1)], G-Ferrara [β57(E1)Asn→Lys (AAC>AAA or AAG)], St. Luke’s [α95(G2)Pro→Arg, C CG>C GG (α1)], Maputo [β47(CD6)Asp→Tyr (GAT>TAT)] and Etobicoke [α84(F5)Ser→Arg (AG C>AG G or CGC or AGA) (α2 or α1)] were also identified. Many children with Hbs Stanleyville-II and Hasharon also co-inherited the −α^3.7 thalassemia gene. African ancestry was recognized by parents of all 31 children with Hb Stanleyville-II who were interviewed. Mean corpuscular volume (MCV) and mean corpuscular Hb (MCH) values were significantly lower in children with α-thalassemia (α-thal). We came to the conclusion that Hb Stanleyville-II is not so uncommon in Brazil and seems to have originated from the African slave trade. This study reinforces the importance of an accurate diagnosis of variants that have electrophoretic mobility similar to Hb S [β6(A3)Glu→Val, GAG>GTG] so that false diagnoses are avoided.

• Hb Stanleyville-II
• Sickle cell disease
• Gene sequencing
• Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP)
• Newborn Screening

ACKNOWLEDGMENTS

The authors would like to thank all family members for participating in the study. The authors would also like to thank Beatriz Carvalho and Terezinha D’Ávila, Fundação Hemominas, Minas Gerais, Brasil, for their technical assistance. This study was supported by FAPEMIG (Fundação de Amparo à Pesquisa do Estado de Minas Gerais, Minas Gerais, Brasil). Marcos Borato Viana has a research grant from CNPq (Brasilian Research Council), Brasil.

Declaration of Interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of this article.