Table 1. Population characteristics.

Description	No. Individuals	No. Families
Total	367a	66
Number of affected individuals/family	2.77±0.99 [2]–[6] b
Sex
Female	223	65
Male	144	61
CMI
Affected	183	66
Female	124	60
Male	59	44
Unaffected/Uncertain	184	61
Female	99	51
Male	85	53
Syringomyelia
Affected	50	41
CMI-Affected	47	40
Female	26	24
Male	21	19
CMI-Unaffected/Uncertain	3	3
Female	2	2
Male	1	1
Unaffected/Uncertain	317	65
CMI-Affected	136	62
Female	98	53
Male	38	32
CMI-Unaffected/Uncertain	181	60
Female	97	50
Male	84	53
Posterior fossa decompression surgery c
Yes	91	57
No	53	38
Unknown	39	24
MRI data
Available	126	50
CMI-Affected	95	49
CMI-Unaffected/Uncertain	31	21
Unavailable	241	65
CMI-Affected	88	52
CMI-Unaffected/Uncertain	153	54

^aOnly considered genotyped individuals after exclusions were applied (See Methods section for details).

^bMean +/− standard deviation [range].

^cOnly considered affected individuals.

Abbreviations: CMI: Chiari Malformation Type I; No.: number.