Discussion
The combined existence of hemophilia A and B is an extremely rare
occurrence. It has been reported due to the inheritance of one variant
from each parent or due to two variants from a single parent. Genetic
studies from a few case reports showed denovo additional mutation of the
genes with underlying congenital hemophilia A or B.5,6
Apart from inherited deficiency of factors, factor inhibition may also
cause depletion of specific factors. Mixing study is used to determine
the presence of any inhibitor in the blood of the patient. The
correction of aPTT after 50:50 mix, easily rules out the possibility of
inhibition.7 After the possibility of factor
inhibition is excluded, unreasonable bleeding with adequate replacement
of factor products for the primary diagnosis was an entry point to
suspect the possibility of this very rare incidence in case reports.
In a single case report from Lithuania, a patient who was known to have
FIX deficiency since childhood, whereas hemophilia A was confirmed at
the age of 42 years due to unexpected bleeding due to dental extraction
despite adequate replacement with factor VIII concentrate. The
deficiency was finally confirmed by genetic study showing point mutation
in exon 2 for f9, whereas f8 gene analysis showed a point mutation in
exon 4. The mother of the patient was heterozygous for f8 mutation, but
not for f9. This suggests the denovo f9 mutation without any family
history.8
Another case report from India, a 16-years-old male patient presented
with knee hemarthrosis, with factor level assay showed both factor VIII
and IX were below 1%. However, the detailed family history of the
patient revealed no incidence of bleeding, which made it similar to the
case we presented above. Genetic test was not done for this patient due
to lack of the test in the center he was diagnosed. The patient was
given both factor VIII and IX , after which the aPTT
normalized.9
Patients with co-existing deficiency of both factor VIII and IX were
also treated with factor replacement based on the severity of the
particular factors. Because of the rare co-occurrence of hemophilia A
and B, the prognosis and long-term treatment outcome of these subgroups
of people is not known.