Scott craniodigital syndrome is a condition that has only been found in two families. The manifestations include unusual head shape, growth and developmental delay, and mild webbing between the fingers and toes (syndactyly)
Individuals with Scott craniodigital syndrome have a combination of mental and growth retardation, minor craniofacial anomalies, and mild webbing between the fingers and toes. Birth weight and length are typically within normal limits, but subsequent growth retardation occurs.
Affected individuals have a broad, short head (brachycephaly). In addition, they have long eyelashes, a small chin, a small and pointed nose, and a thin upper lip. Partial soft tissue webbing occurs between fingers two and four and between toes two and three.
Affected children may also exhibit incomplete closure of bones in the spinal column surrounding the spinal cord (spina bifida occulta). The severity of the condition depends upon whether there is involvement of the spinal cord in the affected area.
There is moderate developmental delay, with children generally walking after age two years. Speech occurs, but is also delayed.
Scott craniodigital syndrome is believed to be inherited as an X-linked recessive genetic trait, based on the presence of the condition in males only. Carrier females have very mild manifestations. Only two families have been described with the condition, so the true gene frequency is unknown.
Chromosomes, which are present in the nucleus of human cells, carry the genetic information for each individual. Human body cells normally have 46 chromosomes. Pairs of human chromosomes are numbered from 1 through 22 and the sex chromosomes are designated X and Y. Males have one X and one Y chromosome and females have two X chromosomes. Each chromosome has a short arm designated “p” and a long arm designated “q”. Chromosomes are further sub-divided into many bands that are numbered. For example, “chromosome 11p13″ refers to band 13 on the short arm of chromosome 11. The numbered bands specify the location of the thousands of genes that are present on each chromosome.
Genetic diseases are determined by the combination of genes for a particular trait that are on the chromosomes received from the father and the mother.
Recessive genetic disorders occur when an individual inherits the same abnormal gene for the same trait from each parent. If an individual receives one normal gene and one gene for the disease, the person will be a carrier for the disease, but usually will not show symptoms. The risk for two carrier parents to both pass the defective gene and, therefore, have an affected child is 25% with each pregnancy. The risk to have a child who is a carrier like the parents is 50% with each pregnancy. The chance for a child to receive normal genes from both parents and be genetically normal for that particular trait is 25%. The risk is the same for males and females.
All individuals carry 4-5 abnormal genes. Parents who are close relatives (consanguineous) have a higher chance than unrelated parents to both carry the same abnormal gene, which increases the risk to have children with a recessive genetic disorder.
X-linked recessive genetic disorders are conditions caused by an abnormal gene on the X chromosome. Females have two X chromosomes but one of the X chromosomes is “turned off” and all of the genes on that chromosome are inactivated. Females who have a disease gene present on one of their X chromosomes are carriers for that disorder. Carrier females usually do not display symptoms of the disorder because it is usually the X chromosome with the abnormal gene that is turned off. A male has one X chromosome and if he inherits an X chromosome that contains a disease gene, he will develop the disease. Males with X-linked disorders pass the disease gene to all of their daughters, who will be carriers. A male cannot pass an X-linked gene to his sons because males always pass their Y chromosome instead of their X chromosome to male offspring. Female carriers of an X-linked disorder have a 25% chance with each pregnancy to have a carrier daughter like themselves, a 25% chance to have a non-carrier daughter, a 25% chance to have a son affected with the disease, and a 25% chance to have an unaffected son.
In females who inherit a single copy of the disease gene for Scott craniodigital syndrome (heterozygotes), disease traits on the X chromosome may not always be masked by the normal gene on the other X chromosome; as a result, these females may exhibit some of the symptoms associated with this disorder. Heterozygous is a condition in which a person has two different genes (alleles) at the same place on matched chromosomes. An individual who is heterozygous for a particular trait has inherited a gene for that trait from one parent and the alternative gene from the other parent. An individual heterozygous for a hereditary disorder produced by a recessive gene will not show the disease or will have a milder form.
Scott Craniodigital Syndrome With Mental Retardation is an extremely rare inherited disorder that is fully expressed in males only. However, females who carry a single copy of the disease gene (heterozygotes) may exhibit some of the symptoms associated with the disorder. The disorder has been reported in two separate families (kindreds) in the medical literature. Most of the symptoms are apparent at birth.
Scott Craniodigital Syndrome With Mental Retardation may be diagnosed at birth, based upon a thorough clinical evaluation and identification of characteristic physical findings.
The treatment of this disorder is directed toward the specific symptoms apparent in each individual. Treatment may require the efforts of a team of specialists who will work together to systematically and comprehensively plan an affected child's treatment. Such specialists may include pediatricians, specialists who diagnose and treat skeletal disorders (orthopedists), neurologists, orthopedic and plastic surgeons, physical and occupational therapists, and/or other healthcare professionals.
Specific therapies for the treatment of this disorder are symptomatic and supportive. For example, in some cases, surgery may be performed to correct certain craniofacial abnormalities. In addition, various orthopedic techniques may be used to help treat and/or correct the foot deformity (talipes varus) associated with this syndrome.
Early intervention is important in ensuring that children with Scott Craniodigital Syndrome With Mental Retardation reach their potential. Services that may be beneficial may include special remedial education, vocational training, and other medical and/or social services.
Genetic counseling will also be of benefit for affected individuals and their families. Other treatment is symptomatic and supportive.
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Gorlin RJ, Cohen MM Jr, Levin LS, eds. Syndromes of the Head and Neck. 3rd ed. Oxford University Press, London, UK; 1990:908.
Buyce ML. editor-in-chief. Birth Defects Encyclopedia. Blackwell Scientific Publications. Center for Birth Defects Information Services, Inc., Dover, MA; 1990:458.
Toriello HV, Higgins JV. Craniodigital syndromes: report of a child with Filippi syndrome and discussion of differential diagnosis. Am J Med Genet. 1995;55:200-04.
Lorenz P, Hinkel GK, Hoffmann C, et al. The craniodigital syndrome of Scott: report of a second family. Am J Med Genet. 1990;37:224-26.
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McKusick VA, ed. Online Mendelian Inheritance in Man. The Johns Hopkins University. Scott Craniodigital Syndrome with mental Retardation. Entry Number; 312860: Last Edit Date; 5/18/1999.