What is Dandy-Walker syndrome?

Quick Answer
Dandy-Walker syndrome is a brain deformity present at birth consisting of a deformity of the cerebellum and the presence of a cyst in the lower portion of the brain. The deformity involves an area in the back of the brain that controls movement and cognitive learning. In many cases, there is also an abnormal accumulation of cerebrospinal fluid within the ventricles of the vein. The symptoms of this syndrome may develop suddenly or may go unnoticed.
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Risk Factors

Dandy-Walker syndrome may be inherited; therefore, having a parent with Dandy-Walker syndrome may increase the risk of occurrence in his or her children. Aside from association with certain inherited genetic conditions, there are no known risk factors. The following factors are associated with Dandy-Walker syndrome, but do not increase the risk of its occurrence: absence of the corpus callosum, which connects the brain’s hemispheres; and malformations of the heart, face, limbs, fingers, and toes.

Etiology and Genetics

Dandy-Walker syndrome is a complex condition with highly variable expression, and there appear to be multiple genetic and environmental factors that can contribute to its manifestation. The best evidence for genetic involvement centers around two adjacent genes found on the long arm of chromosome 3 at position 3q24. These two genes, known as ZIC1 and ZIC4, appear to play a role in the development of the cerebellum. The proteins encoded by these genes are known as zinc finger protein of cerebellum 1 and 4. Cytogenetic analysis indicates that several patients exhibit a small deletion of part of the long arm of chromosome 3 that includes the 3q24 band. Researchers have identified homologous genes and proteins in mice and shown that mice with similar chromosomal deletions present with Dandy-Walker-like symptoms. There is considerable optimism that the establishment of an effective mouse model system will hasten the understanding of the genetic factors contributing to this malformation. Sporadic reports in the literature suggest that deletions of the 2q36.1 chromosomal region or deletions on chromosome 9 and the X chromosome may also be associated with Dandy-Walker syndrome.

In all cases where deletion of a chromosomal segment on chromosomes 2, 3, or 9 have been identified, the inheritance pattern will follow a classic autosomal dominant pattern. An affected individual has a 50 percent chance of transmitting the mutation to each of his or her children. In the majority of cases, however, where the genetic and environmental contributing factors are unknown, no predictable pattern of inheritance is possible.

Symptoms

Symptoms of Dandy-Walker syndrome often occur in infancy but can also occur in older children. According to the US National Library of Medicine's Genetics Home Reference in 2014, between 80 and 90 percent of cases present signs and symptoms of the syndrome within the first year of life. Symptoms may include impaired development of normal speech and language, slow motor development, irritability, vomiting, convulsions, unsteadiness, lack of muscle coordination, and jerky eye movements. Other symptoms may include an increased head circumference; bulging of the back of the skull; problems with the nerves that control the eyes, face, and neck; and abnormal breathing. Children with this condition may have problems with other organs, including heart malformations, kidney and urinary tract abnormalities, cleft lip, and extra digits.

Screening and Diagnosis

The doctor will ask about a patient’s symptoms and medical history and will perform a physical exam. The doctor will also likely do a computed tomography (CT) scan or magnetic resonance imaging (MRI) scan to view the inside of the brain.

Treatment and Therapy

Patients should talk with their doctors about the best plans. Treatment will depend on the problems caused by the syndrome. This may involve placing a special tube called a shunt inside the skull to drain excess fluid in order to reduce pressure and help control swelling.

Prevention and Outcomes

There is no known way to prevent Dandy-Walker syndrome.

Bibliography

Burton, Barbara K. “Dandy-Walker Malformation.” Congenital Malformations: Evidence-Based Evaluation and Management. Eds. Praveen Kumar and Burton. New York: McGraw, 2008. Print.

Gasco, Jaime, and Remi Nader. The Essential Neurosurgery Companion. New York: Thieme, 2013. Digital file.

Genetics Home Reference. "Dandy-Walker Syndrome." Genetics Home Reference. NIH/NLM, 14 July 2014. Web. 18 July 2014.

McCoy, Krisha. "Dandy-Walker Syndrome." Health Library. EBSCO, 13 Feb. 2014. Web. 18 July 2014.

National Institute of Neurological Disorders and Stroke. "NINDS Dandy-Walker Syndrome Information Page." NINDS. NIH/NINDS, 14 Feb. 2014. Web. 18 July 2014.

Schmahmann, Jeremy D., and Eugen Bolthauser. Cerebellar Disorders in Children. London: Mac Keith, 2012. Digital file.

Sarnat, H. B., and L. Flores-Sarnat. “Developmental Disorders of the Nervous System.” Neurology in Clinical Practice. Eds. Walter G. Bradley et al. 5th ed. 2 vols. Philadelphia: Butterworth, 2008. Print.

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