Identification of fetal dna and fetal cell markers in maternal plasma or serum

Abstract

The present invention relates to the identification of fetal specific nucleic acids and fetal cell markers in maternal plasma or serum. In particular, the present invention relates to methods which rely on the analysis of polymorphic alleles of a population to determine an allele which is possessed by the fetus but absent from the mother. Fetal specific alleles identified using the methods of the invention can be used to quantify fetal DNA from maternal plasma or serum. In addition, antigens encoded by alleles identified using the methods of the invention can be targeted in methods of isolating or detecting fetal cells.

1 .- 43 . (canceled) 
     
     
         44 . A method of identifying an allele of a fetal cell, said allele not being present in maternal cells, the method comprising;
 i) identifying alleles which are not present in maternal cells,   ii) obtaining a sample from the mother comprising fetal and maternal nucleic acids, and   iii) screening nucleic acids from the sample for at least one allele not present in the maternal cells.   
     
     
         45 . A method of identifying an allele of a fetal cell, said allele not being present in maternal cells, the method comprising;
 i) obtaining a sample from the mother comprising fetal and maternal nucleic acids,   ii) typing at least one locus from the sample obtained in step i),   iii) comparing the alleles identified in step ii) with alleles of the same locus possessed by the mother, and   iv) selecting an allele typed in step iii) which is not possessed by the mother.   
     
     
         46 . The method of  claim 44 , wherein the father is not typed for any alleles. 
     
     
         47 . The method of  claim 44 , wherein the sample is obtained during the first trimester of pregnancy. 
     
     
         48 . The method of  claim 44 , wherein if the mother has not been typed for an allele before the method is performed the method further comprises typing alleles of at least one locus from maternal cells. 
     
     
         49 . The method of  claim 48 , wherein the typing is performed by obtaining a genomic DNA sample from the mother and exposing the DNA to amplification and/or sequencing procedures. 
     
     
         50 . The method of  claim 48 , wherein the typing is performed by using antibodies which bind the protein products of specific alleles. 
     
     
         51 . The method of  claim 48 , wherein typing alleles of at least one locus from maternal cells is performed on nucleated blood cells, saliva or hair follicles. 
     
     
         52 . The method of  claim 44 , wherein the father is typed for alleles at the same locus/loci as the mother, and alleles are identified which are not present in the mother but which are present in the father. 
     
     
         53 . The method of  claim 44 , wherein the allele is from an HLA locus. 
     
     
         54 . The method of  claim 44 , wherein the sample is derived from plasma, serum or urine. 
     
     
         55 . The method of  claim 44 , wherein the sample is subjected to affinity chromatography to enrich nucleic acids from the sample. 
     
     
         56 . The method of  claim 44 , wherein numerous potential alleles at a particular locus are investigated in the sample simultaneously by a multiplex amplification procedure. 
     
     
         57 . The method of  claim 44 , wherein nucleic acid in the sample is DNA or RNA. 
     
     
         58 . The method of  claim 44 , wherein the mother is a mammal. 
     
     
         59 . The method of  claim 58 , wherein the mammal is a human. 
     
     
         60 . A method of quantifying fetal specific nucleic acids in a sample comprising fetal and maternal nucleic acids, the method comprising identifying an allele which is present in the DNA of a fetal cell but absent from maternal DNA using a method of claim  1 , and determining the concentration of the allele in the sample. 
     
     
         61 . The method of  claim 60 , wherein the allele is quantified by exposing the sample to a nucleic amplification procedure which specifically amplifies the allele, and detecting the amplification product. 
     
     
         62 . The method of  claim 61 , wherein the allele is an HLA allele.