US1

[US1-01] X-Chromosome Inactivation in Facial Development

〇Maiko Kawasaki¹ (1. Div Oral Anat, Niigata Univ Grad Sch Med Dent Sci)

Keywords:X染色体不活性化、顔面発生、OFD1

Mammals have two sex chromosomes, XY (male) and XX (female), and females have two X chromosomes. Therefore, the gene content of the female X chromosome is twice as large as that of the male X chromosome. To correct this imbalance in gene content between male and female X chromosomes, the gene content is corrected by inactivating one of the female X chromosomes. This is called "X chromosome inactivation." When X chromosome inactivation occurs, two chromosomes are randomly inactivated, with one cell inactivating the paternal X chromosome and the other inactivating the maternal X chromosome. This process is irreversible: once an X chromosome of paternal or maternal origin is inactivated, the same X chromosome is inactivated in all the descendant cells of that cell. In other words, all tissues of the female become a mosaic of two types of cells. Only the information from the gene on one of the activated X chromosomes appears as a phenotype. Some genes involved in the developmental process of the maxillofacial region that are present on the sex chromosome will also be affected by this X chromosome inactivation. In some diseases, the causative gene is located on the X chromosome, suggesting that X chromosome inactivation may affect symptoms. In this study, we focus on the OFD1 gene located on the X chromosome, which is the causative gene of Orofacial finger syndrome type 1 and has been reported to cause severe symptoms including oral and facial deformities, hand and finger deformities, central nervous system disorders, and visceral diseases. Transgenic mice with a site-specific deletion of Ofd1 showed a very similar phenotype of Orofacial finger syndrome type 1. In this symposium I will present X chromosome inactivation in facial development by using this transgenic mice model.