The human body has 20,000 genes. Genes are like little machines that make protiens. FoxG1 is one of those genes that is responsible for development of the brain.
While mutations in genes are more common than is percived , resulting in minor changes like differences in colour of our eyes or hair, sometimes errors or mutations on critical genes like the FoxG1 gene result in profoundly debilitating conditions.
The error on genes is like one mising link in a chain tha is say 2 kiloneters long.
With phenomenal advances in computing and nanotechnology, gene sequencing or checking has become very affordable and so the causes of many previously undiagnosable conditions is becoming more apparent. As an example Kushara was the first child in Sydney ever to be diagnosed with FoxG1 syndrome and No5 in Australia.