Microphthalmia with brain and digit anomalies

Microphthalmia with brain and digit anomalies, also known as Microphthalmia, Syndromic 12 (MCOPS12) or sometimes referred to as Syndromic microphthalmia type 12, is an extremely rare genetic disorder characterized by the combination of severe eye malformations, brain abnormalities, and digit (finger and toe) anomalies. The condition is caused by mutations in the RARB gene, which encodes retinoic acid receptor beta, a protein critical for embryonic development. Retinoic acid signaling plays a fundamental role in the development of multiple organ systems during fetal life, and disruption of this pathway leads to the multi-system features seen in this condition. The hallmark ocular feature is microphthalmia (abnormally small eyes) or anophthalmia (absence of one or both eyes), which can cause significant visual impairment or blindness. Brain anomalies may include agenesis or hypoplasia of the corpus callosum, intellectual disability, and other structural central nervous system malformations. Digit anomalies can range from syndactyly (fused fingers or toes) to other limb malformations. Additional features may include congenital diaphragmatic hernia, pulmonary hypoplasia, and cardiac defects in some patients. The condition is typically apparent at birth due to the visible eye and limb abnormalities. There is currently no cure for this condition, and management is supportive and symptomatic. Treatment involves a multidisciplinary approach including ophthalmologic care (prosthetic eyes if needed), neurodevelopmental support, surgical correction of digit anomalies or diaphragmatic hernia when indicated, and early intervention programs to optimize developmental outcomes. Genetic counseling is recommended for affected families.

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