Two factor XI mutations in a Chinese family with factor XI deficiency

We describe a Chinese family with factor XI deficiency, the first reported to date. The proband had factor XI activity of 1% and was heterozygous for two nonsense mutations, an exon‐8 C713→T mutation resulting in Gln263→Term, and an exon‐10 C979→A mutation resulting in Tyr351→Term. Two daughters were heterozygous for the Gln263→Term mutation and two for the Try351→Term mutation. All showed a reduction of factor XI activity to about 50%. The Gln263→Term mutation has been described in two Japanese families, and it remains to be determined whether a common founder exists between the three kindreds. The Try351→Term mutation is novel. Am. J. Hematol. 74:136–138, 2003. © 2003 Wiley‐Liss Inc.