Table 1

Clinicopathological characteristics of the study population.

Clinicopathological parameters	Disease severity
	Severe	Moderate	Mild
	(Factor IX <1%), N=102 (68%)	(Factor IX 1–5%), N=30 (20%)	(Factor IX >5%), N=18 (12%)
Mean factor IX levels (%)	0.6±0.2	2.5±1.3	8.0±2.6
Family history of bleeding (N)	80	10	7
Mean age of onset (yr)	2.0±1.0	7.5±2.8	10.0±3.5
Mutation frequency (within group)	48% (49/102)	86.7% (26/30)	83.3% (15/18)
Inhibitor-positive (N)	23	11	4
Inhibitor-negative (N)	79	19	14
Hemoglobin concentration	Normal	Normal	Normal
Platelet count	Normal	Normal	Normal
Prothrombin time	Normal	Normal	Normal
Activated partial thromboplastin time	High	High	High
Bleeding sites
Joints	55 (54%)	19 (63.3%)	12 (66.7%)
Gum	17 (16.7%)	6 (20%)	4 (22.2%)
Muscle	13 (12.7%)	1 (3.3%)	2 (11.1%)
Epistaxis	7 (6.9%)	4 (13.3%)	0
Petechiae	10 (9.8%)	0	0