Our genes are the instructions for how our bodies grow and develop. They are held in structures called chromosomes and contain long sequences of a molecule called DNA (deoxyribonucleic acid). DNA is made up of a sequence of bases, known as the letters A, C, T and G, which make up the genetic code. We have two copies of each chromosome, one inherited from our mother and one from our father.
In Floating-Harbor syndrome, there are changes (known as ‘mutations’) to the sequence of letters within a gene called SRCAP on chromosome 16. Often these changes only affect one letter within the sequence to cause the condition. Only one copy of the gene needs to be affected for an individual to have the condition; this is known as autosomal dominant inheritance. The vast majority of individuals with Floating-Harbor syndrome have a genetic change which started in them by chance, and was not inherited from either of their parents. Geneticists refer to this as a ‘de novo’ change.