Overview of the location of the mutations in the B3GALTL gene and the results of the RT-PCR of RNA isolated from fibroblasts. A, Genes present in the 1.5-Mb deletion found in two brothers with Peters Plus syndrome. B, 15 exons of the B3GALTL gene, with the localization of the mutations. C, B3GALTL protein, which consists of a transmembrane region (TMR), a stem region (SR), and a catalytic domain (CD). Both mutations (c.1020+1G→A and c.437+5G→A) are located in the stem region. D, Result of the nested RT-PCR of exons 7–11 of the BGALTL gene, with RNA derived from myoblasts (WT), RNA from fibroblasts of a father heterozygous for the c.1020+1G→A mutation (Het), and RNA from fibroblasts of his affected son with c.1020+1G→A_pat/del_mat (Hom). The patient shows a smaller band compared with the WT band, which indicates a skip of exon 8. Sequence analysis of this band is shown. The vertical line indicates the end of exon 7 and the beginning of exon 9. The RT-PCR of the father shows, in addition to the WT band, a skipped product with much less intensity. E, Result of the RT-PCR encompassing exons 4–7 of the BGALTL gene, with RNA derived from lymphocytes of a control individual (WT) and a patient with a c.1020+1G→A_mat/c.437+5G→A_pat genotype (Het). In addition to a faint WT band, the patient shows a smaller product that lacks exon 5. The sequence analysis of this smaller band confirms the skip of exon 5.

Facial features of four patients with Peters Plus syndrome. Patients A and C are homozygous for the c.1020+1G→A mutation. Patient B has the c.1020+1G→A_mat/c.437+5G→A_pat genotype, and patient D has the c.1020+1G→A_pat/del_mat genotype. Note the Peters anomaly of the eyes, the long face, and the Cupid’s bow shape of the upper lip in all patients. Patients B and D have a repaired cleft lip and/or palate. Patient A is female; the rest are male.