Table 2.

Data on chromosomal position (X linked vs autosomal) and proportions of genes inferred as subject to recent positive selection, as evidenced by selective sweeps in humans, for mental retardation genes with different biological functions as listed in Inlow and Restifo (2004), Appendix 1

Biological function	X-linked	Autosomal	P (exact)	Selected, this function	Selected, other functions	P (exact)
CNS	23/34	104/214	0.043	18/123	15/130	0.58
Lysosomal	2/44	27/225	0.19	3/29	29/240	1.0
DNA repair	0/44	9/227	0.36	4/9	29/255	0.016
Metabolic	10/44	85/227	0.083	9/94	24/170	0.34
Transcription regulation	3/43	18/226	0.76	3/21	30/241	0.74
Signaling pathway	13/43	20/226	0.0004	2/30	31/232	0.39
Protein modification	0/44	17/224	0.084	3/17	30/244	0.46

Fisher's exact test was used to compare proportions. Biological functions listed as uncertain (with a “?”) in Inlow and Restifo (2004), Appendix 1 are not included in the compilations, and seven genes have data on chromosomal location and biological function, but no data on the presence or absence of positive selection.