Schematic presentation of the B3GALTL gene structure and overview of the mutations identified in patients with PPS. Novel mutations are indicated in bold above the gene diagram; previously reported mutations are indicated below the gene diagram. The B3GALTL transcript is 4254-bp in size (1497-bp for the coding region) and consists of 15 exons. Each exon is represented by a box with its size (bp) indicated on top. The N-terminal domain is shown as a vertically striped box, the stem region is shaded in light grey, the catalytic domain is shaded in dark grey and the catalytic core is indicated in black. Deletions of B3GALTL are indicated at the bottom of the drawing; previously reported deletions were identified using array-based comparative genomic hybridization approach and included B3GALTL and five additional genes, HSPH1, LGR8, LOC196545, FRY, and BRCA2, in one case (2) and B3GALTL and four additional gene, USPL1, ALOX5AP, C13orf23, HSPH1, in another study (6); the deletion in Patient 1 in this study was identified using B3GALTL-specific TaqMan copy number assays (Supplemental Figure 1), thus the full extent of the deletion is unknown.