Blood Group Antigen Gene Mutation Database

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Scianna Blood Group System

Introduction

Antigens reside on a type I membrane glycoprotein, of moleular weight 60-68 kDa. The protein is named Human erythroblast membrane protein (HERMAP); it belongs to the butyrophilin-like subset of the immunoglobulin superfamily. It is encoded by the ERMAP gene that spans 19kb. Two high prevalence antigens Sc1 and Sc3 and two low prevalence Sc2 and Sc4 (Radin) specify the Scianna blood group system.

The genes

At least two the ERMAP gene transcripts have been identified that differ in the 5' region and in size as a result of alternative splicing and the use of different promoters.The longer transcript 1 shows 12 exons and the shorter transcript 2, spans 11 exons, but both transcripts share the ATG start codon in exon 3 and both show the same coding sequence.

Function of proteins

It has been suggested that Ermap may play a putative role in a number of immunological processess such as cell adhesion, costimulation or signaling. A role in erythropoiesis has also been proposed.

Tissue distribution

Expressed on erythrocytes, and weakly expressed in leukocytes, thymus, lymph nodes, spleen. Also present in fetal liver and adult bone marrow.

Disease association

Not known; anti-Sc2 and anti-Rd may cause hemolytic disease of the newborn.

Historical aspects

A recent historical review by Brunker and Flegel is now available (Immunohematology 2011 27 41)

About the alleles

The system is comprised of two anthithetical high prevalence (99%) antigens, Sc1 and Sc3 and two low prevalence antigens, Sc2 (1% among Northern Europeans) and Sc4 (also known as Rd ). The very rare null Sc:-1,-2,-3 phenotype is characterized by the absence of Sc1, Sc2 and Sc3 antigens. In the list of alleles, the sequence acc. no. AY049028 is taken as reference; it is the sequence of the shorter transcipt2 and it encodes the Sc1 antigen.

When searching for a particular allele, use "name" if DNA alteration is known or, if you wish to search by phenotype or numerical terminology or the designation used by author, use "alias" (see "Details").

Other database IDs and links

Literature

Excellent recent review: Brunker and Flegel, immunohematology 2011 27 41-57.

New PubMed entries with the terms Scianna and blood from the last 30 days.
NCBI Book Sections with the terms Scianna and blood.

Contributors

Marion E. Reid and Christine Lomas-Francis, Immunohematology, New York Blood Center, 310 East 67 St., New York, N.Y., 10021; More recently, Blumenfeld OO.

Contributors for specific alleles are listed with the alleles.

Links