The Human body is not an impeccable machine; many conditions affect our functioning and our development as we grow. One such condition is Dandy-Walker Syndrome. It affects brain development, more especially, the primary development of the cerebellum. This abnormal development results in the vermis (central part of the cerebellum) being unusually small or absent or in an unusually large posterior fossa (part of the skull that contains the cerebellum). All these abnormalities cause problems in movement, coordination or intellect, resulting in an impediment for a normal development of a person.
It is not rare that these abnormalities present themselves in the first year of life; actually the syndrome is presented in 1 out of 25,000 newborns. Typically when the disorder presents itself at this early age the intra-cranial fluid of the children builds up and it generates macrocephaly (increased head size). Other malformations are less common, they include holoprosencephaly which results in the hemispheres of the brain failing to separate, schizencephaly resulting in abnormal slits or clefts in the brain, among others. It is estimated that only 20% of people with Dandy-Walker Syndrome will live past the first year of life and the primary causes are mostly because of complications in treatment. Because the cerebellum controls most of the bodies motor functions, serious heart conditions are also associated with Dandy-Walker Syndrome
There are some investigations and researchers that claim that mutations in a few specific genes are the cause for Dandy-Walker Syndrome. But these mutations are only found in certain specific abnormalsymptoms of the syndrome, so no conclusion in this respect had been drawn so far. Another theory researchers have is the possibility that Dandy-Walker Syndrome is caused because of an abnormal chromosomal presence. This abnormality is called trisomy and means that an additional copy of a chromosome is present in each cell, in Dandy-Walker Syndrome this abnormality is most recurrent in trisomy 18, meaning that chromosome 18 is the one that is duplicated in each cell. It has been reported that Dandy-Walker is also present in newborns that present a different condition called triploidy, meaning that they have present a full duplicated set of chromosomes in each cell; this condition is fatal by itself.
Most cases are irregular and with no prior family history, the general conclusion is that this particular syndrome is not inherited by genetics alone. If it is present from one generation to another it was only because multiple factors influenced this "passing" of the disorder and is not common for it to happen. So, there is not a certain cause for this disorder and medicine researchers are still trying to figure out which can be the trigger its symptoms and, most importantly, the syndrome itself.