Examples of such abnormalities include dwarfism (having a severely short stature), dislocated elbows, decreased joint mobility, muscular hypotonia (having weak muscle tone), and involuntary muscle stiffness.They may also exhibit abnormal conditions at their skin and teeth. Moreover, a portion of affected males may demonstrate cryptorchidism (a condition in which the testes fail to descend into the scrotum). Causes
Filippi syndrome is a genetic disease with an autosomal recessive inheritance pattern at the Cytoskeleton Associated Protein 2 Like (CKAP2L) gene. Inheritance pattern
An autosomal recessive inheritance pattern means that the disease trait is exhibited on an individual only when both copies of the disease gene in the individual demonstrate a specific pathogenic mutation. This happens when the individual inherits one copy of the mutated gene from each of their parents. In the case of Filippi Syndrome, both copies of the CKAP2L gene of an individual have to be mutated in order for them to demonstrate symptoms of the disorder. CKAP2L gene
The CKAP2L gene is the human ortholog of the mouse CKAP2I (Radmis) gene. It contains 10 exons and is located on chromosome 2q14.1. It is a protein-coding gene that is associated with microtubules and some cellular structures involved in mitosis. The CKAP2L gene is essential for the proper formation of mitotic spindles during mitosis and the progression of the cell cycle of human cells. The expression pattern of the CKAP2L gene can explain the occurrence of syndactyly in Filippi Syndrome. Mutations
Multiple mutations at the CKAP2L gene can cause Filippi Syndrome.
Brachydactyly is believed to be largely due to abnormalities arising from the bones inside the hands and feet, specifically the metacarpals and metatarsals. Craniofacial abnormalities
Furthermore, most people with Filippi Syndrome exhibit craniofacial abnormalities. Craniofacial abnormalities are birth defects observed at the head or face region of affected individuals. Some of the craniofacial abnormalities present in people with Filippi Syndrome include microcephaly (having a skull that is smaller than normal), prominent/ elevated nasal bridge, hypertelorism (having ones pair of eyes further apart from each other than normal), and underdeveloped nasal alae (underdeveloped tissues surrounding the nostril). Less common craniofacial abnormalities include having a broad forehead, thin vermilion border (having a thin upper lip), and frontal hirsutism (having a hairy forehead). Mental retardation
People with Filippi Syndrome may also demonstrate varying degrees of intellectual disability. Affected individuals may experience defective speech development, aphasia (experiencing difficulty in finding the appropriate words to use), vision impairment, and an inability to speak. Growth retardation
Another characteristic symptom of people with Filippi Syndrome is the occurrence of growth retardation, which is also referred to as growth delay. Such growth delays may be either prenatal or postnatal, meaning that they can occur both before and after birth. In particular, delayed bone maturation can be observed in patients with Filippi Syndrome. Other symptoms
People with Filippi Syndrome may exhibit some other physical abnormalities.