In patient 2, a 5,807-kb deletion was identified including XG, GYG2, ARSD-AS1, ARSD, ARSE, ARSH, ARSF, LINC01546, MXRA5, PRKX, PRKX-AS1, LOC389906, LOC101928201, NLGN4X, LOC105373156, MIR4770, VCX3A, PUDP, MIR4767, STS, VCX-A, PNPLA4, MIR651, VCX2, VCX3B, and ANOS1. In 1986, Ballabio et al. (1986) reported that variations in the XG gene were associated with XLI. Here, PUDP is linked to recessive X-linked ichthyosis.