title: Weak D in the Tunisian population.
abstract: BACKGROUND
  More than 90 weak D types have been discovered to date. As there are no published data on the frequencies of weak D types in the Tunisian population, the aim of this study was to determine the composition of weak D alleles in our population.
  
  
  METHODS
  Blood samples from 1777 D+ and 223 D- blood donors were tested for markers 809G, 1154C, 8G, 602G, 667G, 446A, and 885T relative to translation start codon by polymerase chain reaction with sequence-specific primers to estimate the frequencies of weak D type 1, weak D type 2, weak D type 3, weak D type 4, weak D type 5 and weak D type 11 in our population. Twenty-three samples with positive reactions were re-evaluated by DNA sequencing of RHD exons 1-10 and adjacent intronic sequences.
  
  
  RESULTS
  Among the D+ donor cohort, weak D type 4 was the most prevalent allele (n=33, 1.2%) followed by weak D type 2 (n=6, 0.17%), weak D type 1 (n=4, 0.11%), and weak D type 5 (n=1, 0.28%) and weak D type 11 (n=1, 0.28%). RHD sequencing identified a weak D type 4.0 allele in all 19 samples tested. Among the D- pool, comprising 223 samples, we detected one sample with weak D type 4.0 associated with a C+c+E-e+ phenotype which had been missed by routine serological methods.
  
  
  CONCLUSIONS
  Weak D type 4.0 appears to be the most prevalent weak D in our population. However, all samples must be sequenced in order to determine the exact subtype of weak D type 4, since weak D type 4.2 has considerable clinical importance, being associated with anti-D alloimmunisation. One case of weak D type 4 associated with dCe in trans had been missed by serology, so quality control of serological tests should be developed in our country.
authors.affiliation: Regional Blood Transfusion Centre, Sousse, Tunisia.
authors.forename: Mouna
authors.initials: M
authors.lastname: Ouchari
authors.affiliation: Regional Blood Transfusion Centre, Sousse, Tunisia.
authors.forename: Houda
authors.initials: H
authors.lastname: Romdhane
authors.affiliation: Regional Blood Transfusion Centre, Sousse, Tunisia.
authors.forename: Taher
authors.initials: T
authors.lastname: Chakroun
authors.affiliation: Regional Blood Transfusion Centre, Sousse, Tunisia.
authors.forename: Saida
authors.initials: S
authors.lastname: Abdelkefi
authors.affiliation: Regional Blood Transfusion Centre, Sousse, Tunisia.
authors.forename: Batoul
authors.initials: B
authors.lastname: Houissa
authors.affiliation: National Blood Transfusion Centre, Tunis, Tunisia.
authors.forename: Slama
authors.initials: S
authors.lastname: Hmida
authors.affiliation: Regional Blood Transfusion Centre, Sousse, Tunisia.
authors.forename: Saloua Jemni
authors.initials: SJ
authors.lastname: Yacoub
mesh_terms: D000483:Alleles; D001782:Blood Donors; D015331:Cohort Studies; D005260:Female; D005838:Genotype; D006801:Humans; D008297:Male; D012204:Rh-Hr Blood-Group System / Q000235:genetics*; D014416:Tunisia
chemical_list: D012204:Rh-Hr Blood-Group System; C026410:Rho(D) antigen