Figure 4. .

Chromosome-engineered and Rai1-knockout mouse models of SMS. Left, Genomic structure of the critical region on human 17p11.2 and the syntenic interval in mouse. The two chromosome homologues, represented by horizontal lines, are shown for each of the five strains studied, including wild type (WT) (A), three chromosome-engineered deletions with the region deleted demarcated by an absent horizontal line flanked by parenthesis at the break points (B–D), and the Rai1-knockout allele marked by an asterisk (E). Top, Individual genes within the interval examined. The shaded gray background represents the experimentally manipulated chromosome, whereas the fixed or constant chromosome is not shaded. Right, Details of the five strains studied. Note that there is essentially no change in penetrance for the deletion mutants (boxes), whereas there is reduced penetrance (triangle) for the knockout allele. NA = not available. ND = not determined.