Heavy transfusions and presence of an anti-protein 4.2 antibody in 4. 2(-) hereditary spherocytosis (949delG)

Abstract

BACKGROUND AND OBJECTIVE: A patient with hereditary spherocytosis (HS) was found not to have red cell membrane protein 4.2. This rare form of HS, or 4.2 (-) HS, stems from mutations within the ELB42 or the EPB3 genes. The patient had long suffered from a gastric ulcer and impaired liver function. He had had several dramatic episodes of gastrointestinal tract bleeding and had received numerous transfusions. An antibody against a high frequency, undefined antigen was found, creating a transfusional deadlock. We elucidated the responsible mutation and searched for an anti-protein 4.2 antibody. DESIGN AND METHODS: Red cell membranes were analyzed by SDS-PAGE and by Western blotting. Nucleotide sequencing was performed after reverse transcriptase-polymerase chain reaction (RT-PCR) and nested PCR. RESULTS: The not previously described mutation was a single base deletion: 949delG (CGCAECC, exon 7, codon 317) in the homozygous state. It was called protein 4.2 Nancy. The deletion placed a non-sense codon shortly downstream so that no viable polypeptide could be synthesized. The patient carried a strong antibody against protein 4.2 as shown by Western blotting. INTERPRETATION AND CONCLUSIONS: The manifestations resulting from the mutation described were compared with the picture of HS stemming from other ELB42 gene mutations. We discuss the mechanism through which the anti-protein 4.2 antibody developed. There was no way to establish or to rule out whether the antibody participated in the transfusional deadlock found in our patient.