FOXP1 syndrome is considered a rare disease that is caused by a mutation or change to the FOXP1 gene. The gene is located on chromosome 3 and includes the instructions or “recipe” for making the Forkhead BOXP1 protein. As a member of a family of transcription factors, it is vital in regulating the expression of other genes. FOXP1 controls when and how specific genes affect the development of the nervous system, along with many other systems. When a gene like FOXP1 does not function properly it can lead to a wide range of developmental delays and medical needs.
What causes FOXP1 Syndrome?
Chromosomes are the structures that carry an individual’s genetic information. This information is encoded by units called genes, which can be thought of as long words made up of strings of 4 different “letters” (A, G, T, and C). Genes are arranged along the chromosome like words in a sentence. In humans, each cell normally contains 23 pairs of chromosomes, for a total of 46 chromosomes. Twenty-two of these pairs (autosomes) look the same in males and females. The 23rd pair (sex chromosomes) differs between sexes. Humans usually have two copies of every gene on the autosomes, including FOXP1.
FOXP1 syndrome is caused by genetic lesions (mutations) of the FOXP1 gene.
These include a swap of a single letter or loss or gain of a few letters on one copy of the gene, as well partial or total deletions of one copy of the gene. The disorder is referred to as "autosomal dominant" because mutations of a single copy of FOXP1 are enough for a person to be affected. FOXP1 mutations typically arise
spontaneously in affected individuals (that is, not inherited), and are therefore
referred to as “de novo” mutations. Because the parents would typically have two
normal copies of the FOXP1 gene, there is a very small chance to have a second
child with FOXP1 syndrome.
How common are FOXP1 gene mutations?
FOXP1 mutations are rare, but more and more cases are being identified as genetic testing becomes more widespread. There are online parent groups including RareConnect and Facebook with several hundred families represented. There are likely many more people carrying mutations in the gene who have not yet been diagnosed.