An HphI-polymorphism in exon 28 of the von Willebrand factor gene, and its frequency among patients with various forms of von Willebrand's disease.
Besides having a large number of restriction fragment length polymorphisms (RFLP) the von Willebrand factor (vWF) gene contains several sequence polymorphisms in the coding regions. Eight nucleotide substitutions have been reported in two or more independent cDNA clones. Four of them give rise to amino acid substitutions, two of which are in the mature vWF subunit (at positions 26 and 709). We have investigated a previously suggested putative alanine-threonine polymorphism at position 618 of the mature subunit in normal subjects and patients with various types of von Willebrand's disease (vWD). the codon for amino acid 618 is located in exon 28, which encodes several important vWF functional domains. We amplified the whole exon 28 and parts of it by polymerase chain reaction (PCR) and distinguished gene from pseudogene sequences. The alanine----threonine (G----A) substitution was studied with restriction enzyme cleavage of the products, since it creates a new HphI site. Moreover, in two individuals we confirmed the polymorphism by cDNA sequencing. In 23 normals the frequencies of the h- (Ala) and the h+ (Thr) alleles were 0.50/0.50. In eight patients with type III vWD from seven different families, the h- allele was present in 13 of 16 genes, but whether this signifies a common mutation in some of the patients is not known. In types I and II, both alleles were present in roughly similar proportions. Owing to the high frequency of heterozygosity, the polymorphism should prove useful as an aid in genetic counselling.
Donnér
M
M
Department of Paediatrics, University Hospital, Lund, Sweden.
Holmberg
L
L
Kristoffersson
A C
AC
Nilsson
I M
IM
D001483:Base Sequence; D004247:DNA / Q000032:analysis*; D004277:DNA, Single-Stranded; D015252:Deoxyribonucleases, Type II Site-Specific; D005091:Exons; D005787:Gene Frequency; D006801:Humans; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic / Q000235:genetics*; D014842:von Willebrand Diseases / Q000235:genetics*; D014841:von Willebrand Factor / Q000235:genetics*
D004277:DNA, Single-Stranded; D014841:von Willebrand Factor; D004247:DNA; D015252:Deoxyribonucleases, Type II Site-Specific; C024412:GGTGA-specific type II deoxyribonucleases