Table 2.

Idiopathic scoliosis (IS) incidence in various-degree relatives

	No.	Onset number A	Incidence (q%)	U value	P value
First-degree relatives	589	59	10.01%	21.46	<.01
Second-degree relatives	1,532	39	2.55%	5.81	<.01
Third-degree relatives	397	7	1.76%	1.38	>.05
Total number of relatives	2,518	109	4.25%	15.89	<.01
Total investigated families	2,732	321 (including probands)	11.74%	56.32	<.01
Control population			1.04%

A absolute number of relatives with IS