Table 4.
Diabetes concordance rates in pairs of MZ twins, DZ twins, and siblings with CF
| Median age (yr) | Diabetes status of pair
|
Concordancea | |||
|---|---|---|---|---|---|
| Both | One | Neither | |||
| MZ twin pairs | 18.3 (n = 68) | 11 | 4 | 53 | 0.73 |
| DZ twin pairs | 11.7 (n = 23) | 0 | 3 | 20 | 0.00 |
| Sibling pairs | 13.7 (n = 588) | 13 | 69 | 506 | 0.16 |
| DZ and sibling matched to MZb | 17.3 (n = 136) | 4 | 18 | 114 | 0.18 |
| Diabetes concordance rates after accounting for steroid use ≥ 30 dc | |||||
| MZ twin pairs | 18.3 (n = 66) | 8 | 1 | 47 | 0.89 |
| DZ and sibling pairs | 13.4 (n = 579) | 6 | 47 | 430 | 0.11 |
| DZ and sibling matched to MZb | 17.1 (n = 128) | 2 | 13 | 90 | 0.13 |
| Diabetes concordance rates after accounting for ABPAd | |||||
| MZ twin pairs | 17.9 (n = 57) | 8 | 1 | 48 | 0.89 |
| DZ and sibling pairs | 15.4 (n = 499) | 10 | 46 | 443 | 0.18 |
| DZ and sibling matched to MZb | 18.2 (n = 107) | 4 | 12 | 91 | 0.25 |
Six sibling pairs known to differ in CFTR genotype were excluded. Diabetes status of a pair was categorized as ″Both″ members having diabetes, ″One″ of two members having diabetes or ″Neither″ member having diabetes.
Concordance for diabetes was defined as the number of pairs in which both members had diabetes divided by the number of pairs in which one or both had diabetes.
Same-sex DZ twin pairs combined with same-sex, age-corrected sibling pairs. Age correction was done by considering the diabetes status of the older member at the age of the younger member. From this group were selected 136 pairs matched for age, sex, and pancreatic insufficiency to the 68 MZ pairs. Pairs did not differ in age (P = 0.4) or any other matched variable.
Pairs in which exactly one member had steroid treatment 30 d or more (i.e. discordant for steroid treatment) were excluded.
Pairs in which exactly one member had ABPA were excluded.