TABLE 2:

Age and MR measurements from symptomatic fragile X premutation carriers and control participants

	Age (yr)	Pons AP (mm)	Pons Trans (mm)	Pons RC (mm)	MCP R (mm)	MCP L (mm)	IV Height (mm)	Ant Horn (mm)	Fr. Cereb-Vent Index	Evan’s Index	III Width (mm)
Control participants
Average	66.1	26	31	29	18	18	11	36	0.32	0.28	6.1
Maximum	76.0	28	33	31	19	22	14	40	0.35	0.31	9.0
Minimum	56.0	23	27	26	15	14	10	31	0.28	0.24	4.0
SD	6.1	1.7	1.7	1.4	1.1	1.9	1.2	2.7	0.02	0.02	1.4
Patients
Average	67.6	22	25	26	13	13	12	44	0.40	0.35	11.2
Maximum	77.0	24	31	29	17	17	16	60	0.50	0.46	15.0
Minimum	59.0	19	19	23	9	9	8	23	0.30	0.25	7.0
SD	4.7	1.2	2.9	1.8	2.0	2.0	2.5	8.0	0.05	0.05	2.7
P value	0.46	<.005	<.005	<.005	<.005	<.005	0.21	<.005	<.005	<.005	<.005

Note.—AP indicates anteroposterior; Trans, transverse; RC, rostral-caudal; MCP, middle cerebellar peduncle; R, right; L, left; IV Height, vertical dimension of the fourth ventricle measured from the floor of the fourth ventricle to its apex on a midline sagittal image; Ant Horn, maximal width of both anterior horns; Fr. Cereb-Vent Index, ratio of maximal width of both anterior horns to the diameter of inner table of skull along the line of measurement of anterior horn transverse dimension; Evan’s index, ratio of maximal width of both anterior horns to the diameter of inner table of skull at its point of greatest transverse diameter on any image; III Width, width of third ventricle; Note that MCP R and MCP L are the narrowest oblique transverse dimension of the right and left middle cerebellar peduncles measured from an axial image. P values were derived from Student’s t test of control versus patient populations.