Hb Yaoundé [beta134(H12)Val-->Ala] in association with Hb C [beta6(A3)Glu-->Lys] in a Caucasian Portuguese family.
Hb Yaoundé [beta134(H12)Val-->Ala] is a rare, silent and asymptomatic hemoglobin (Hb) variant. It was previously reported in a Black man from Cameroon, in association with Hb Kenitra [beta69(E13)Gly-->Arg], and was subsequently found and described as Hb Mataro in a sub-Saharan child. To date, Hb Yaoundé has not been described in Caucasian people and molecular studies have never been performed. Here we describe a three-generation Caucasian Portuguese family in whom Hb Yaoundé was found in association with Hb C [beta6(A3)Glu-->Lys] (in the proband) and in a heterozygous state (in the proband's mother). The Hb studies of the proband's hemolysate, performed by isoelectric focusing (IEF) and low-pressure cation exchange chromatography, only revealed an Hb variant identified as Hb C by comparison with a control. However, analysis performed by reversed-phase high-performance liquid chromatography (HPLC) showed two different beta chain variants and a complete absence of the normal beta chain. This uncommon Hb variant was identified as Hb Yaoundé by DNA sequencing analysis of the beta-globin gene (codon 134, GTG-->GCG). The beta-globin gene haplotypes were determined in all family members using polymerase chain reaction (PCR)-based methodology; Hb Yaoundé was found to be associated with the Mediterranean haplotype II. This study is the first description of Hb Yaoundé in Caucasian individuals, and its association with a Mediterranean haplotype supports the hypothesis of an independent genetic origin other than African.
Faustino
Paula
P
Laboratório de Biologia Molecular, Centro de Genética Humana, Instituto Nacional de Saúde Dr. Ricardo Jorge, Lisboa, Portugal. paula.faustino@insa.min-saude.pt
Miranda
Armandina
A
do Céu Silva
Maria
M
Alves
Cristina
C
Picanço
Isabel
I
Ferreira
Cristina
C
Seixas
Maria Teresa
MT
Pina
Francisca
F
Romão
Luísa
L
D002852:Chromatography, Ion Exchange; D005190:Family; D005260:Female; D006239:Haplotypes / Q000235:genetics*; D006444:Hemoglobin C / Q000032:analysis / Q000235:genetics*; D006455:Hemoglobins, Abnormal / Q000032:analysis / Q000235:genetics*; D006579:Heterozygote; D006801:Humans; D007525:Isoelectric Focusing; D008297:Male; D010375:Pedigree; D011174:Portugal; D044465:White People
D006455:Hemoglobins, Abnormal; C434205:hemoglobin Yaounde; D006444:Hemoglobin C