Molecular identification of Rh variants
Date Issued
2012
Date
2012
Author(s)
Chan, Io-Meng
Abstract
Rh blood type system has found as another important blood system besides ABO blood type system, the most important antigens in Rh blood type system are D, C, c, E, e, the antigen is the reason for many different Rh blood in worldwide.
Rh gene locates in chromosome 1, two genes are involved : RHD and RHCE, the first is for antigen D, and the second is for antigen C/c and E/e, the antigen epitope of C/c antigen is Exon2 of RHCE gene, and the antigen epitope of E/e antigen is Exon5 of RHCE gene, In the other hand, two gene are highly homologous, so that in the same allele, two genes can have gene conversion because of the pair between RHCE and RHD gene. Furthermore, upstream and downstream Rhesus box which flank the RHD gene can make the RHD gene lost due to the unequal crossing by Rhesus box between two alleles; and now we know the Rh blood type system is very complicated, and it is worth for us to study the molecular mechanism and the genotype.
Our study focuses on the patients (Case 6 & 7) which Rh blood type is D+C-E-c-e-, one Rh-negative patient (Case 8) and five normal sample (Case 1~5) , and my aim is the genotype of Rh gene. First we analyze the blood type by antigen and antibody reaction, then we used the website NCBI to search the RHD and RHCE hole gene sequence and compare it to the difference of two genes and the polymorphism between C/c antigen and E/e antigen. After all, we design some pair of primers which targets on exon to analyze the difference between normal and sample’s Rh gene.
As the sequence of RHD and RHCE genes we predict by website, the polymorphism between C/c antigen and E/e antigen are observed in all normal’s genes sequence; in the patient’s result, Case 6’s gene sequence is only RHD gene except Exon 1 and 10 , Case 7’s gene sequence is only RHD gene except Exon 1, 9 and 10, Case 8’s gene sequence is only RHCE gene except Exon 2.
According to the study result, we make a hypothesis that Case 6 and 7 are the hybrid gene, the genotype of case 6 is RHCE-D(2-9)-CE, the genotype of case 7 is RHCE-D(2-7/8)-CE or RHCE-D(2-9)-CE , and this is the reason for the C/c and E/e antigen disappear, and case 8, the Rh-negative phenotype is responsible for two possible molecular mechanism, one is two alleles which RHD gene is deleted, and one of alleles is RHCE hybrid gene, another one is gene conversion or gene deletion, and we shall study more in the future.
Subjects
Rh
molecular
Type
thesis
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