Table 3. SMN gene copy numbers observed in 25 core families.

Case no.	Clinical type	SMN1/SMN2 ratio
		Patient	Father	Mother	Sib
1	I	0:2(M)	1:1	1:1 or1:2a
2	I	0:2(F)	1:1	1:2
3	I	0:2(M)	1:2	1:1
4	I	0:2(F)	1:3	2:0a
5	I	0:3(M)	2:1b	1:3
6	I	0:2(M)	1:2	1:1 or1:2a
7	I	0:2(F)	1:1	1:2
8	I	0:3(M)	1:2	1:3
9	I	1D:3(M)	1+1D:2	1:3	2:2(F)
10	I	0:2(M)	1:1	1:2
11	I	0:2(M)	1:2	1:1
12	I	0:2(M)	1:2	1:3
13	I	0:2(F)	1:2	1:3
14	II	0:3(M)	1:2	1:3
15	II	0:3(M)	1:3	1:1
16	II	0:3(F)	2:1b	1:3
17	II	0:3(M)	1:1	1:2 or 1:3a
18	II	0:3(F)	1:2	1:3
19	III	0:4(F)	1:2	1:3	0:2(F)
20	III	0:3(M)	1:2	1:3
21	III	0:3(F)	1:3	1:2 or 1:3a
22	III	0:3(F)	1:1	1:3
23	III	0:4(M)	1:3	1:2 or 1:3a
24	III	0:4(F)	1:3	1:3
25	III	1D:3(F)	1+1D:1	1:3

M, male; F, female.

^aBlood samples were not available from these individuals, and therefore their SMN genotypes were assumed based on the genotypes determined for their patients and fathers from the family study.

^bThese two fathers were found to be the ‘carriers with the ‘2+0' genotype by the further family testing.