SBDS Western blot. (A) Proteins extracted from normal cyropreserved blood leukocytes were analyzed by immunoblotting with the SBDS antiserum either directly (none) or after immunoprecipitation with SBDS or control antiserum. There are 2 bands of approximately 29 kDa that are detected in whole-cell extracts. The upper band but not the lower band is efficiently immunoprecipitated by the SBDS antiserum, suggesting that the upper band represents the SBDS protein. (B,C) Protein extracts of cyropreserved blood leukocytes from family members in the registry were analyzed by immunoblotting with the SBDS antiserum (upper panels) or an actin antibody (lower panels). SBDS genotypes are lanes 1, 2, and 9: normal; lanes 3, 4, 5, and 10: 183-184TA>CT × 258+2T>C; lane 6: 258+2T>C × 505C>T; lanes 7 and 8: normal with clinical diagnosis of possible SDS; lanes 11 and 13: normal × 258+2T>C; and lane 12: normal × 183-184TA>CT. The relative densitometry signal for the SBDS band compared with the actin band is shown for lanes 9 to 13. Molecular size markers are indicated at the left in kilodaltons. These data are representative of 2 independent experiments using the same protein extracts.