title: Frequency of null allele of Human Leukocyte Antigen-G (HLA-G) locus in subjects to recurrent miscarriage.
abstract: BACKGROUND
  Human leukocyte antigen-G (HLA-G) is a non-classical class I molecule highly expressed by extravillous cytotrophoblast cells. Due to a single base pair deletion, its function can be compensated by other isoforms. Investigating the frequency of null allele in Recurrent Miscarriage (RM) subjects could be useful in understanding the relationship between frequency of this allele and RM in a given population.
  
  
  OBJECTIVE
  This study aimed to determine the frequency of HLA-G*0105N null allele and its potential association with down-regulation of HLA-G in subjects with RM.
  
  
  METHODS
  Western blotting was used to assess the level of HLA-G protein expression. For investigating the frequency of HLA-G*0105N null allele in RM subjects, PCR-RFLP method was used. Exon 3 of HLA-G gene was amplified by polymerase chain reaction (PCR). Subsequently, PpuM-1 enzyme was employed to digest the PCR products and fragments were analyzed using gel electrophoresis.
  
  
  RESULTS
  Digestion using restriction enzyme showed the presence of heterozygous HLA-G*0105N null allele in 10% of the test population. Western blotting results confirmed the decrease in expression of HLA-G in the placental tissue of subjects with RM compared to subjects who could give normal birth.
  
  
  CONCLUSIONS
  The frequency of heterozygous HLA-G*0105N null allele was high to some extent in subjects with RM. The mutation rate in subjects suggested that there is a significant association between RM and frequency of mutations in this allele.
authors.affiliation: Immunology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran.; Nazila Alizadeh and Elnaz Mosaferi contributed equally to this work and both are first author.
authors.forename: Nazila
authors.initials: N
authors.lastname: Alizadeh
authors.affiliation: Immunology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran.; Nazila Alizadeh and Elnaz Mosaferi contributed equally to this work and both are first author.
authors.forename: Elnaz
authors.initials: E
authors.lastname: Mosaferi
authors.affiliation: Women Reproductive Health Research Center, Tabriz University of Medical Sciences, Tabriz, Iran.
authors.forename: Laya
authors.initials: L
authors.lastname: Farzadi
authors.affiliation: Immunology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran.
authors.forename: Jafar
authors.initials: J
authors.lastname: Majidi
authors.affiliation: Department of Hematology, Faculty of Medicine, Tabriz Branch, Islamic Azad University, Tabriz, Iran.
authors.forename: Amir
authors.initials: A
authors.lastname: Monfaredan
authors.affiliation: Students Research Committee, Tabriz University of Medical Sciences, Tabriz, Iran.
authors.forename: Bahman
authors.initials: B
authors.lastname: Yousefi
authors.affiliation: Immunology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran.
authors.forename: Behzad
authors.initials: B
authors.lastname: Baradaran
keywords: Allele; HLA-G*0105N; RFLPs; Recurrent miscarriage