Microphthalmia with linear skin defects syndrome

Microphthalmia with linear skin defects (MLS) syndrome, also known as MIDAS syndrome (Microphthalmia, Dermal Aplasia, and Sclerocornea), is a rare X-linked dominant genetic disorder that is typically lethal in males. The condition is characterized by two hallmark features: microphthalmia (abnormally small eyes) or anophthalmia (absent eyes), and linear skin defects present at birth, which appear as areas of aplastic skin (erythematous, linear streaks) predominantly on the face and neck. These skin lesions typically heal over time, leaving hyperpigmented scars. MLS syndrome primarily affects the eyes, skin, and in many cases, the heart and brain. Ocular abnormalities may include sclerocornea, corneal opacities, orbital cysts, and other structural eye defects that can lead to significant visual impairment or blindness. Cardiac defects, including cardiomyopathy, oncocytic cardiomyopathy, and various structural heart malformations, are frequently reported. Neurological features may include agenesis of the corpus callosum, microcephaly, and intellectual disability, though cognitive function can be normal in some individuals. Additional features may include short stature, diaphragmatic hernia, and nail abnormalities. The syndrome is caused by mutations or deletions involving genes on the short arm of the X chromosome (Xp22.2), most commonly the HCCS gene (encoding holocytochrome c-type synthase) and, less frequently, the COX7B gene. Because the condition is typically lethal in hemizygous males, the vast majority of affected individuals are female. Treatment is supportive and symptom-based, including ophthalmologic interventions, cardiac monitoring and management, dermatologic care for skin lesions, and developmental support as needed. Genetic counseling is recommended for affected families.

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