Summary
In this report we describe the molecular basis of the factor IX (FIX) deficiency in
nine patients with severe (n = 6), moderate (n = 1) or mild (n = 2) hemophilia B.
The following genetic defects were identified by enzymatic amplification with the
polymerase chain reaction (PCR) and subsequent direct sequencing of all exons and
exon-intron-junctions: patient B.B. (FIX “Vienna I”): deletion of nucleotides 6343
to 6362; patient M.H. and W. J. (FIX “Vienna II”): nucleotide 17704 (C to G), Gin
97 to Glu; patient L. K. (FIX “Vienna III”): nucleotide 17761 (C to T), Arg 116 to
stop; patient U. A. (FIX “Vienna IV”): nucleotide 10415 (C to G), Pro 55 to Ala; patient
H.G. (FIX “Vienna V”): nucleotide 6488 (C to T), Thr 38 to lie; patient H. M. (FIX
“Vienna VI”): nucleotide 31276 (G to C), Trp 385 to Cys; patient L. C. (FIX “Vienna
VII”): deletion of nucleotide 6700; patient S.F. (FIX “Vienna VIII”): nucleotide 10392
(A to T), Asp 47 to Val. The causative mutation was detected in the FIX gene in each
of the nine patients with hemophilia B. There was one small deletion, one point deletion
and seven point mutations. The latter include six missense mutations and one nonsense
mutation. The mutations in Vienna III, IV and V have already been described in previous
studies. The two deletions, Vienna I and Vienna VII have not been reported previously.
The genetic defects observed in Vienna II, VI and VIII are novel missense mutations
which result in amino acid changes at residues 97,47 and 385, respectively.
