A large X‐chromosomal deletion is associated with microphthalmia with linear skin defects (MLS) and amelogenesis imperfecta (XAI)

A female patient is described with clinical symptoms of both microphthalmia with linear skin defects (MLS or MIDAS) and dental enamel defects, having an appearance compatible with X‐linked amelogenesis imperfecta (XAI). Genomic DNA was purified from the patient's blood and semiquantitative multiplex PCR revealed a deletion encompassing the amelogenin gene (AMELX). Because MLS is also localized to Xp22, genomic DNA was subjected to array comparative genomic hybridization, and a large heterozygous deletion was identified. Histopathology of one primary and one permanent molar tooth showed abnormalities in the dental enamel layer, and a third tooth had unusually high microhardness measurements, possibly due to its ultrastructural anomalies as seen by scanning electron microscopy. This is the first report of a patient with both of these rare conditions, and the first description of the phenotype resulting from a deletion encompassing the entire AMELXgene. More than 50 additional genes were monosomic in this patient. © 2009 Wiley‐Liss, Inc.