Congress of the International Society on Thrombosis and Haemostasis

T33P substitution and W519X mutation in two turkish patients with FXI deficiency

Abstract number: PP-MO-653

Caglayan¹ H., Usluer¹ S., Pekcelen² Y., Berber³ E., Aksu⁴ S.

¹¹Molecular Biology and Genetics, Bogazici university ²²Faculty of Medicine, Istanbul University ³³Molecular Biology and Genetics, Halic University, Istanbul ⁴⁴Faculty of Medicine, Hacettepe University, Ankara, Turkey

How-to-cite Caglayan H, Usluer S, Pekcelen Y, Berber E, Aksu S. T33P substitution and W519X mutation in two turkish patients with FXI deficiency. Journal of Thrombosis and Haemostasis 2009; Volume 7, Supplement 2: Abstract PP-MO-653

Congenital Factor XI (FXI) deficiency is a rare bleeding disorder, characterized by bleedings after trauma or surgery. FXI deficiency is inherited as an autosomal recessive trait. However, some autosomal dominant cases have recently been reported. Bleeding diathesis due to Factor XI deficiency is variable and does not correlate with the plasma FXI activity. Normal FXI:C plasma level varies between 75–150 U dL-1. Mutations within the F11 gene have been associated with the FXI deficiency. In this study, we report the mutational analysis of the F11 gene in two patients with low FXI levels using direct DNA sequence analysis of the coding regions, the promotor region and intron-exon junctions. The first patient had 18 U dL-1 FXI level, prolonged aPTT (42 min) but no bleeding problems. The patients F11 gene analysis revealed a previously reported c.1556G > A substitution which created a stop codon in exon 13 (W519X) in heterozygous condition. The patient also had substitutions at codons 217 (Gly217Ser) and 283 (Phe283Leu, TypeIII mutation). However, these changes need to be confirmed by PCR and DNA sequencing. The second patient had 24 U dL-1 FXI plasma level. The F11 gene sequence analysis revealed c.151A > C change in one allele which resulted in the T33P substitution in the protein sequence. Threonine at position 33 is conserved in mammals and other serine proteases and the mutation was previously observed in one patient. The patient did not have any other sequence change in the F11 gene.

Disclosure of interest: none declared.

To cite this abstract use the following format:

Journal of Thrombosis and Haemostasis 2007; Volume 5, Supplement 2: abstract number

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Session name:	ISTH2009
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