Coffin-Siris syndrome is a rare congenital disorder that affects more females than males. Individuals with this syndrome have some degree of mental retardation or developmental delay, a coarse facial appearance, incompletely formed or absent fifth fingernails, and absent fifth fingers (distal phalanges). The cause of this disorder is unknown, and the severity of symptoms varies by individual.
Coffin-Siris syndrome was first described in 1970 by Dr. Grange S. Coffin and Dr. Evelyn Siris. It may also be known as fifth digit syndrome. The cause of the disorder is unknown, and the combination of symptoms may vary by individual. All affected children have some form of mental retardation or developmental delay, and incompletely formed (hypoplastic) or absent fifth fingernails and tips of the fifth fingers (distal phalanges). There are some reports of fingers other than the fifth being affected, and affected toes and toenails. The face of a child with Coffin-Siris syndrome is usually described as coarse. This includes a flat nasal bridge, broad nose, wide mouth, thick lips, and in some cases, thick eyebrows, long eyelashes, palate malformations, a large tongue (macroglossia), and a small head (microcephaly). While some infants have an abnormal facial appearance, most of the facial features become more prominent as the child grows. Typically, there is sparse scalp hair in the infant and excessive growth of body hair (hirsutism). Reduced muscle tone (hypotonia), lax joints, delay in bone maturation, and short stature are commonly found. There are reports of frequent upper respiratory and ear infections. Occasionally, children with this disorder have cardiac or spinal abnormalities, hernias, vision or hearing problems, or delayed tooth development (dentition).
Infants with Coffin-Siris syndrome typically have sucking problems and feeding difficulties that may continue as they age. The extent of growth and mental retardation varies by individual. Mental retardation is usually reported as moderate. There are delays in motor activities such as rolling over, sitting up, and walking. Speech is usually delayed. Most children are more capable of responding to speech, rather than verbally expressing themselves.
At present, the cause of Coffin-Siris syndrome is unknown. Most children reported with this disorder have a normal chromosome set (karyotype ). There are a few cases in which a transfer of genetic material between chromosomes (translocation) has occurred. This may provide information about a specific chromosome site responsible for Coffin-Siris syndrome, but it has not been found in many individuals.
The majority of cases are sporadic, or random, in which the parents and siblings of an affected child are all healthy. However, there are some cases of affected siblings, and parental relatedness (consanguinity). Coffin-Siris syndrome was originally thought to follow an autosomal recessive pattern of inheritance . This would mean that both healthy parents were carriers for the disorder, and the affected child inherited the affected gene from both parents. However, there are some reported cases that do not follow this pattern. An exact pattern of inheritance is unknown. The recurrence risk may be as high as 25%.
At present, there are reports of more than 60 individuals affected with Coffin-Siris syndrome. It is more common in females, and the female to male ratio may be as high as a 3:1. There are cases of affected siblings, and parental relatedness. In general, cases are random, with affected children having healthy siblings and parents.
Signs and symptoms
At birth, infants with Coffin-Siris syndrome will have an absence or incomplete formation of the fifth fingernail and tip of the fifth finger (distal phalanx). This absence may also occur in the toes or in other fingers. Infants may have an abnormal facial appearance at birth. As the child grows, the facial abnormalities characteristic of Coffin-Siris syndrome become more apparent. Sparse scalp hair in an infant usually becomes more dense with age and excessive hair growth (hirsutism) develops. Infants typically have sucking problems and feeding difficulties that may continue with age.
There is a delay in both gross and fine motor skills. Developments such as sitting up and walking may be delayed or not possible, depending upon the severity of the disorder. Speech is usually delayed and most children are better able to respond to language rather than express it. Some older children are able to form short sentences and answer simple questions. Mental retardation is usually moderate. Social adaptation is usually delayed.
At present, the diagnosis of Coffin-Siris syndrome is based upon clinical findings. There are no laboratory tests that can confirm the disorder. The combination of symptoms such as coarse facial appearance, fifth finger appearance, and developmental delay would suggest Coffin-Siris syndrome. X ray of the hands to reveal the absence of the fifth finger bone is usually the best indicator of this syndrome. Neonatal ultrasounds for cardiac, kidney (renal), and other malformations that may be present with this disorder can also be informative.
Prenatal ultrasound may show intrauterine (occurring within the uterus) growth retardation, and can reveal the condition of the fifth finger. However, these symptoms alone cannot conclusively lead to a prenatal diagnosis of Coffin-Siris syndrome.
Due to the rarity, range of symptoms, and variability of Coffin-Siris syndrome, a definitive diagnosis may be difficult. It is important to exclude other disorders that may have similar symptoms. These include Coffin-Lowry syndrome , Cornelia de Lange syndrome , fetal hydantoin syndrome, trisomy 9p, and Brachymorphismonychodysplasia-dysphalangism syndrome.
Treatment and management
The treatment or therapy required for children with Coffin-Siris syndrome is based on the particular symptoms of each individual. Some children may require surgery to repair malformations that may be seen with this disorder. This ranges from cleft palate repair to cardiac, renal, or other surgery. Speech therapy and special education may be considered depending upon the degree of mental retardation, developmental delay, and motor impairment.
Infants born with Coffin-Siris syndrome may experience a delay or absence of motor and mental activities, but with support can live into adulthood. The lifestyle of an individual with Coffin-Siris syndrome is dependent to a large extent upon the degree of mental retardation and developmental delay.
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Dimaculangan D.P., et al. "Difficult Airway in a Patient with Coffin-Siris Syndrome." Anesthesia and Analgesia 92 (2001): 554-555.
Fleck, B.J., et al. "Coffin-Siris Syndrome: Review and Presentation of New Cases From A Questionnaire Study." American Journal of Medical Genetics 99 (2001): 1-7.
McPherson E.W., et al. "Apparently Balanced t(1;7)(q21.3;q34) in an Infant With Coffin-Siris Syndrome." American Journal of Medical Genetics 71 (1997): 430-433.
Rabe, P., et al. "Syndrome of Developmental Retardation, Facial and Skeletal Anomalies, and Hyperphosphatasia in Two Sisters: Nosology and Genetics of the Coffin-Siris Syndrome." American Journal of Medical Genetics 41 (1991): 350-354.
National Organization for Rare Disorders (NORD). PO Box 8923, New Fairfield, CT 06812-8923. (203) 746-6518 or (800) 999-6673. Fax: (203) 746-6481. <http://www.rarediseases.org>.
Coffin-Siris Syndrome. <http://members.aol.com/CoffinSiri/index.html>.
Maureen Teresa Mahon, BSc, MFS