Structural study of hemoglobin Knossos, beta 27 (B9) Ala leads to Ser. A new abnormal hemoglobin present as a silent beta-thalassemia.

A new electrophoretically silent hemoglobin variant is described that produces the classical phenotype of beta thalassemic intermedia in association with beta thalassemia trait. This variant has the expression of a silent beta thalassemia trait. The abnormal hemoglobin was detected by acid-urea-Triton-acrylamide electrophoresis and further demonstrated by isoelectric focusing. The amount of the variant in carrier is approximately 30% of the total hemoglobin. No instability was found. Absence of hemoglobin A in the propositus blood facilitated structural studies. Peptides maps were normal but analysis of individual peptide spots showed an Ala leads to Ser substitution in the beta T3. This variant has been previously called Hb Knossos (beta 27 (B9) Ala leads to Ser).

A new silent hemoglobin variant in a black family from French West Indies, hemoglobin Le Lamentin alpha 20 His replaced by Gln.

A new abnormal hemoglobin Hb Le Lamentin alpha 20 (B1) His replaced by Gln was discovered during a survey of cord blood from the French West Indies (Martinique). This variant displays an electrophoretic pattern similar to that of Hb A but can be isolated by isoelectric focusing (IEF) and Biorex 70 chromatography. Family studies showed the presence of this hemoglobin variant in the father and in two of his three children. Hematological data from the carriers were normal.

[Detection of haemoglobinopathies at birth, using isoelectric focalization (author's transl)]. / Dépistage des hémolgobinopathies à la naissance par isoélectrofocalisation. Etude de la population de la martinique.

The incidence and nature of haemoglobinopathies were investigated at birth in Martinique, where 4635 samples of umbilical cord blood were examined. Conventional blood values were determined, and a new, extremely simple and highly selective test was performed: isoelectric focalization. Abnormalities were found in 14.3% of blood samples, viz: A/S 7.25%, A/C 3.17%, S/S 0.17%, S/C 0.24%, C/C 0.04%, other mutations 0.63% alpha-thalassaemia minor (alpha 1-thal) 1.72% and isolated microcytosis 1.01%. Unusual abnormalities included 7 different mutations of the 4a-chain, 3 of the beta-chain and 3 of the gamma-chain. The clinical and epidemiological importance of such investigations is emphasized.

Isoelectric focusing of human hemoglobins.

Isoelectric focusing on thin layer of acrylamide gel has been used for the characterization of 79 different variants of hemoglobin A. This method has replaced the cellulose acetate electrophoresis in clinical laboratories in Martinique, Guadeloupe and Creteil for the detection of abnormal hemoglobins in populations at risk. Up to now 15,000 samples from adults have been evaluated. In addition this method has been used for the screening of 7,000 cord blood samples and for the prenatal diagnosis of severe hemoglobinopathies.