What is Fifth Digit Syndrome?
Fifth Digit Syndrome which is also known by the name of Coffin-Siris Syndrome is an extremely rare genetic pathological condition characterized by various craniofacial abnormalities with distinct facial features.
The distinct facial features include an abnormally small head, wide nose, wide mouth, prominent lips, and very little if any hairs. Additionally, affected individuals with Fifth Digit Syndrome will have an abnormally short fifth digit of the fingers and toes. The nails of such individuals are also underdeveloped and in some cases even absent.
Individuals with Fifth Digit Syndrome also tend to have problems with feeding, have frequent bouts of respiratory infections, and certain ocular abnormalities. There are also certain musculoskeletal abnormalities seen in individuals with Fifth Digit Syndrome in the form of decreased muscle tone or hypotonia and joint laxity.
Children with Fifth Digit Syndrome also tend to have delays in reaching their developmental milestones and have intellectual disability. The symptoms exhibited by individuals with Fifth Digit Syndrome are significantly variable where in some cases the symptoms may be mild while in other cases they may be extremely severe.
Fifth Digit Syndrome is basically caused by mutations in several genes namely ARID1A, ARID1B, SMARCA4, SMARCB1, and SMARCE1. This condition follows an autosomal dominant pattern of inheritance meaning that one copy of the faulty gene from either parent is good enough for an individual to develop Fifth Digit Syndrome.
What are the Causes of Fifth Digit Syndrome?
As stated, the root cause of Fifth Digit Syndrome is mutations in at least five genes namely ARID1A, ARID1B, SMARCA4, SMARCB1, and SMARCE1. The functions of these genes are to produce proteins which regulate gene activity and making sure that the DNA is tightly packed along with regulating cell growth, division, and replication of DNA.
A faulty gene results in the alteration in the packaging of DNA causing the characteristic symptoms of Fifth Digit Syndrome. This condition follows an autosomal pattern of inheritance meaning that one copy of the faulty gene from either parent is good enough for a child to develop Fifth Digit Syndrome.
What are the Symptoms of Fifth Digit Syndrome?
The primary presenting feature of Fifth Digit Syndrome is the distinct facial features exhibited by the affected individual. These include an abnormally small head, distinct facial features which become more prominent as the child grows.
Prominent lips and low nasal bridge is also something that is seen in individuals with Fifth Digit Syndrome. Another primary presenting feature of an individual with Fifth Digit Syndrome is the presence of an abnormally short fifth digit of the finger which gives this condition its name.
The hair in the scalp is also extremely less in individuals with Fifth Digit Syndrome. The nails of individuals with Fifth Digit Syndrome are also either very thin or completely absent.
Additionally, there are also certain musculoskeletal abnormalities in individual with Fifth Digit Syndrome with hypotonia. Children with Fifth Digit Syndrome will tend to have delays in attaining their developmental milestones, tend to have extremely slow growth with very little if any weight gain when compared to other children of the same age. They are also prone to frequent respiratory infections as a result of Fifth Digit Syndrome. There are also certain ocular abnormalities seen in individuals with Fifth Digit Syndrome with ptosis of the upper eyelid, strabismus, and presence of cataracts at an early age as a result of Fifth Digit Syndrome.
How is Fifth Digit Syndrome Diagnosed?
The characteristic physical features seen when the child is born can point towards a diagnosis of Fifth Digit Syndrome. If this condition is suspected then the treating physician may order certain specialized tests to confirm the diagnosis.
Advanced imaging may be done in the form of MRI scans to look for structural abnormalities seen in Fifth Digit Syndrome. Ophthalmologic and hearting evaluations may also be done to confirm the diagnosis. Genetic testing carried out on such children may confirm the mutations in the gene causing this condition thus confirming the diagnosis of Fifth Digit Syndrome.
How is Fifth Digit Syndrome Treated?
The treatment for Fifth Digit Syndrome requires a coordinated effort from a variety of specialists like pediatricians, orthopedists, ophthalmologists, physical therapists, speech and language specialists who can formulate a treatment plan best suited for the patient.
Surgery may be required in individuals to correct certain craniofacial abnormalities and skeletal deformities associated with Fifth Digit Syndrome. The surgical procedures done will depend on the severity and extent of the condition.
If an early diagnosis is made then the chances of a successful outcome of treatment becomes extremely bright in a child with Fifth Digit Syndrome. For speech and feeding difficulties, a speech therapist is of great value in treating these issues associated with Fifth Digit Syndrome.
In some extreme cases where the child is not able to feed independently then placement of an NG tube is recommended to feed the child dealing with Fifth Digit Syndrome.
