Novel double-deletion mutations of the OFD1 gene creating multiple novel transcripts

Oral-facial-digital syndrome type 1 (OFD1) is an X-linked dominant disease characterized by malformations of the face, oral cavity, and digits. Thus far, 18 small mutations in the OFD1 gene have been reported. Here, we describe, in one Japanese sporadic female OFD1 case, the presence of a novel pair of deletion mutations: a 4,094-bp deletion encompassing exon 7 to intron 9, and a 14-bp deletion in intron 9, both of which are present in her paternal X-chromosome. The first deletion, the largest known to affect OFD1, was revealed by identifying four novel transcripts that all lacked exons 7-9. The most likely cause of the double deletion is two unequal recombinations between homologous sequences. Identification of the 4,094-bp deletion was made possible only by analyzing OFD1 mRNA, underscoring the utility of mRNA analysis in the mutational analysis of OFD1.