The difference in disease severity between Hemophilia A and B (HA, HB) was recently assessed in the study, “Clinical, Instrumental, Serological And Histological Findings Suggest That Hemophilia B May Be Less Severe Than Hemophilia A,” and published in Haematologica.
HA and HB are caused by deficient clotting proteins, factor VIII (FVIII) and factor IX (FIX), respectively.
The deficiency leads to a bleeding disorder of severe measures that often includes internal musculoskeletal bleeding and joint damage caused by the bleeding. Joint disease is the most common complication of hemophilia.
“Subjects with factor plasma levels less than 1 IU/dL are classified as severe hemophiliacs, whereas those with factor levels between 1 and 5 IU/dL and more than 5 IU/dL are affected by moderate and mild hemophilia. Although the bleeding phenotype may be rather heterogeneous, this classification reflects closely the severity of clinical symptoms,” the study revealed.
The clinical distinction between HA and HB has long been challenging but some evidence proposes that disease severity in patients with HB might be lower than those with HA. To test the hypothesis, the researchers compared HA with HB through reported differences among several parameters related to clinical, imaging, and biochemical markers.
Study participants included 70 HA and 35 HB patients with at least one joint bleeding, indicative of disease severity. The patients were evaluated and the data were compared.
The results suggested that patients with HA have higher joint bleedings than those with HB. The World Federation of Hemophilia’s Pettersson score was substantially higher in HA patients than those with HB (36.6 vs. 20.2). A similar trend was recorded for joint damage measured through ultrasound scores (10.9 for HA vs. 4.3 for HB).
Biochemical analyses revealed that patients with HA have decreased levels of blood osteoprotegerin and soluble RANK ligand (both important for bone metabolism and resportion) when compared with HB patients. Finally, HA patients showed lower expressed levels of osteoprotegerin than the HB patients.
Overall, the findings demonstrate that disease severity in patients with HA is higher than that of HB patients.
Further, the results suggest that arthropathy (arthritis in one or more joints) is more severe in HA patients; and that synovitis (inflammation of the synovial membrane that lines the joint capsule in the knee, ankle, wrist, elbow, hand, foot, ect..), play a crucial rule in blood induced arthropathy.
The study concluded: “An early clinical, instrumental and serological screening of all hemophiliacs may be recommended. Further investigation of the mechanisms promoting and sustaining blood-induced synovial inflammation will be necessary to shed additional light on the pathogenesis of hemophilic arthropathy.”