Dandy-Walker malformation-postaxial polydactyly syndrome

Dandy-Walker malformation-postaxial polydactyly syndrome is a complex condition characterized by structural brain abnormalities, specifically a posterior fossa cyst communicating with the fourth ventricle and a partial or complete absence of the cerebellar vermis, in combination with extra digits on the hands and sometimes feet. The condition falls under a syndromic group where the brain malformation, known as Dandy-Walker malformation, and postaxial polydactyly are both predominant features. It is classified as very rare, affecting fewer than 1 in a million people. Although the precise genetic basis is under investigation, the condition is inherited in an autosomal recessive manner, meaning that two copies of an altered gene are required for the disorder to manifest.

The clinical presentation in this syndrome centers around the brain malformation and limb anomalies. The Dandy-Walker malformation typically involves a cyst in the posterior fossa with variable involvement of the cerebellar vermis and may lead to hydrocephalus, while postaxial polydactyly most often affects the hands, with extra digits or bifid metacarpals being common. Not all individuals experience all features, and severity varies considerably. Other neurological and developmental outcomes may be influenced by the extent of the brain involvement, making early evaluation essential.

The precise genetic basis of Dandy-Walker malformation-postaxial polydactyly syndrome is currently under investigation. The condition is inherited in an autosomal recessive pattern, which means that a child must receive an altered copy of the gene from each parent to be affected. This condition is more common when parents share a common ancestor, as they are more likely to both carry a rare genetic variant. Families with a history of this syndrome or shared ancestry may benefit from genetic counseling to better understand the risks and implications for future pregnancies.

Currently, management focuses on supportive care and symptom management, with treatment tailored to the individual’s needs. Without any established foundational or targeted therapies specific to this syndrome, a multidisciplinary team approach is generally employed. This may include neurosurgical management for hydrocephalus, orthopedic consultation for limb differences, and developmental therapies to support cognitive and motor skills. Genetic counseling is recommended for families to discuss implications of the autosomal recessive inheritance pattern and to explore reproductive options.

Outcomes for individuals with Dandy-Walker malformation-postaxial polydactyly syndrome vary significantly depending on the severity of the brain malformation and the presence of associated complications. With current standards of care, many individuals receive interventions that help manage symptoms and improve quality of life. That severity and symptoms vary widely between individuals, and while some may experience challenges associated with hydrocephalus or developmental delays, others may have a more stable clinical course. Outcomes described in medical literature continue to evolve as standards of care improve, and families often find it helpful to connect with genetic counselors and specialists familiar with the condition.