The Malmo polymorphism of factor IX: establishing the genotypes by rapid analysis of DNA

Abstract

A DNA polymorphism in the coding region of coagulation factor IX-- potentially valuable for carrier detection, prenatal diagnosis, and population studies--was described in 1985. It had been discovered with monoclonal antibodies that distinguish between threonine and alanine as the 148th residue of the peptide. Its use as a diagnostic tool has been limited because threonine-containing factor IX (Malmo A) is dominant to alanine-containing factor IX (Malmo B) in immunoassays of plasma; therefore, detection of Malmo heterozygotes is not possible in all instances. A DNA method for recognizing all heterozygotes has been developed, but it also has limitations. We report the development of another DNA procedure based on amplification of the relevant DNA with the polymerase chain reaction (PCR). This method is quick, avoids the use of isotopes and x-ray film, and specifically identifies all the Malmo genotypes: hemizygotes, homozygotes, and heterozygotes. The procedure can be performed satisfactorily on small samples of blood (less than 1 mL) as suggested by Kogan et al (N Engl J Med 317:985, 1987). The method described is applicable to any genetic polymorphism that overlaps a restriction enzyme recognition site.

Genetic determinants of normal variation in coagulation factor (F) IX levels: genome‐wide scan and examination of the FIX structural gene

“…Eleven of these polymorphisms, including four in the promoter (G−816A, G−653C, A−634G, and T−609C), five in introns (C10118G, C13162T, G13516A, G30249A, and C30294T), one each in the 3′‐UTR (A32168T) and 3′‐genomic‐DNA (A32781G), were absent from public databases (http://www.kcl.ac.uk/ip/petergreen/haemBdatabase.html; http://pga.gs.washington.edu; http://www.ncbi.nlm.nih.gov/books/bookres.fcgi/handbook/ch5d1.pdf). Of two coding sequence polymorphisms (A20422G, G31093A), both previously known, one encodes a non‐synonymous substitution (Thr148Ala) [28]; G31093A encodes Gln324Gln (Fig. 3C).…”

Why does the mutation G17736A/Val107Val (silent) in the F9 gene cause mild haemophilia B in five Swedish families?

“…Concentrations of F9 antigen (Ag) were measured by applying an ELISA according to the instructions of the manufacturer (DAKO). Restriction fragment length polymorphisms (RFLPs) in the F9 gene were determined using the restriction enzymes Hha I, Taq I, Mnl I, Dde I, Xmn I, Msp I and Bam HI as previously described [11–16].…”

Identification of factor IX gene defects using a multiplex PCR and CSGE strategy—a first report

“…One patient (HB‐95) had four sequence alterations; a 30138delCA in exon h, two previously unreported [1] variants, namely 20616G‐A in intron 6 and a 32847T‐C in the 3′ untranslated region (UTR), and the Malmö polymorphism (20422G‐A, 148, Ala→Thr) [7]. Of these, the 30138delCA frame shift mutation is likely to be the causative mutation.…”