title: Inheritance and bleeding in factor XI deficiency.
abstract: A study of 20 Jewish and four non-Jewish kindreds transmitting factor XI deficiency (164 individuals) confirmed inheritance to be autosomal with severe deficiency in homozygotes (mean factor XI level 3.8 u/dl, SD 2.91) and partial deficiency in heterozygotes (mean factor XI level 57 u/dl, SD 10.42; normal mean factor XI level 96 u/dl, SD 11.6). The probability of an individual being heterozygous can be predicted from the factor XI level using a graph derived from this data. The accuracy is increased by including the prior probability derived from the pedigree. A high frequency of heterozygote to heterozygote mating was observed in the Jewish families consistent with an estimated gene frequency of 13.4% in this racial group. The relationship between factor XI level and bleeding tendency is poor; a third of heterozygotes had bled excessively after surgery, including six with factor XI levels above 50 u/dl, showing this condition to have clear signs of expression in heterozygotes. The lower limit of the normal range (2 SDs from the mean) was found to be 72 u/dl.
authors.affiliation: Academic Department of Haematology, Royal Free Hospital, London.
authors.forename: P H
authors.initials: PH
authors.lastname: Bolton-Maggs
authors.forename: B
authors.initials: B
authors.lastname: Young Wan-Yin
authors.forename: A H
authors.initials: AH
authors.lastname: McCraw
authors.forename: J
authors.initials: J
authors.lastname: Slack
authors.forename: P B
authors.initials: PB
authors.lastname: Kernoff
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D005172:Factor XI / Q000032:analysis; D005173:Factor XI Deficiency / Q000097:blood / Q000235:genetics*; D005260:Female; D006470:Hemorrhage / Q000209:etiology; D006579:Heterozygote; D006720:Homozygote; D006801:Humans; D008297:Male; D008875:Middle Aged; D010375:Pedigree; D012306:Risk
chemical_list: D005172:Factor XI