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.