Two novel point mutations correlate with an altered developmental
expression of blood coagulation factor IX (hemophilia B Leyden phenotype)
PH Reitsma, T Mandalaki, CK Kasper, RM Bertina and E Briet
Department of Hematology, Leiden University Hospital, The Netherlands.
Hemophilia B Leyden is characterized by low levels of factor IX antigen and
activity before the age of 15 years, whereas after puberty factor IX levels
rise at a rate of about 5% per year. Two distinct point mutations (deletion
of A, A----G) were identified at position +13 of the factor IX gene of a
Greek and an American patient with hemophilia B Leyden. The nucleotide
changes have occurred 32 basepairs downstream of a previously reported
point mutation in a Dutch kindred with the same hemophilic phenotype. The
results point to the importance of sequences surrounding the putative start
site for the constitutive expression of the factor IX gene and to the
possible significance of an imperfect direct repeat of DNA.
Volume 73,
Issue 3,
pp. 743-746,
02/15/1989
Copyright © 1989 by The American Society of Hematology
