The probability that consecutive SNPs would be homozygous and concordant by chance in families with two to four individuals in different siblings
| No. SNPs | For two individuals | For two siblings and another individual | For three individuals | For four individuals | ||||
|---|---|---|---|---|---|---|---|---|
| Probability homozygous¶ | Ratio† | Probability homozygous** | Ratio† | Probability homozygous†† | Ratio† | Probability homozygous‡‡ | Ratio† | |
| *The probability that a run of n SNPs are homozygous is 0.7 (the chance a SNP has either an AA or BB allele call), then multiplied by n. | ||||||||
| †The ratio is the probability presented as 1 to y, where y is the probability that n SNPs are consecutively homozygous multiplied by 10 913 − n (the total number of autosomal SNPs, minus the number of SNPs in a run). | ||||||||
| ‡The probability that a run of n SNPs are homozygous and concordant in a sib pair is 0.7 (the chance a SNP has either an AA or BB allele call) multiplied by 0.7 (rather than 0.35, to allow for reduced informativity) for each SNP, then multiplied by n. | ||||||||
| §As note ‡ but 0.7*0.7*0.7 for each SNP, then multiplied by n. | ||||||||
| ¶As note § but 0.7*0.7*0.7*0.7 for each SNP, then multiplied by n. | ||||||||
| ¶The probability that a run of n SNPs are homozygous in two individuals is 0.7 (the chance a SNP has either an AA or BB allele call) multiplied by 0.35 (the chance another individual has the same homozygous allele call), then multiplied by n. | ||||||||
| **As for note ¶ but 0.7*0.35*0.7, then multiplied by n. | ||||||||
| ††As for note ¶, but 0.7*0.35*0.35, then multiplied by n. | ||||||||
| ‡‡As for note ¶, but 0.7*0.35*0.35*0.35, then multiplied by n. | ||||||||
| 1 | 0.245000 | 0.0004 | 0.17150000 | 0.0005 | 0.08575000 | 0.0011 | 0.03001250 | 0.0031 |
| 2 | 0.060025 | 0.0015 | 0.02941225 | 0.0031 | 0.00735306 | 0.0125 | 0.00090077 | 0.10 |
| 3 | 0.014706 | 0.006 | 0.00504420 | 0.018 | 0.00063053 | 0.145 | 0.00002703 | 3.39 |
| 4 | 0.003603 | 0.025 | 0.00086508 | 0.11 | 0.00005407 | 1.695 | 0.00000081 | 113 |
| 5 | 0.000883 | 0.10 | 0.00014836 | 0.62 | 0.00000464 | 20 | 0.00000002 | 3764 |
| 6 | 0.000216 | 0.42 | 0.00002544 | 3.60 | 0.00000040 | 231 | ||
| 7 | 0.000053 | 2 | 0.00000436 | 21 | 0.00000003 | 2689 | ||
| 8 | 0.000013 | 7 | 0.00000075 | 122 | ||||
| 9 | 0.0000032 | 29 | 0.00000013 | 714 | ||||
| 10 | 0.00000078 | 118 | 0.00000002 | 4163 | ||||
| 11 | 0.00000019 | 480 | ||||||
| 12 | 0.00000005 | 1961 | ||||||