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NORD is very grateful to Juan F. Sotos, MD, Endocrinology, Metabolism & Diabetes, Nationwide Children's Hospital, for assistance in the preparation of this report.
Sotos syndrome is a genetic disorder, described in 1964, characterized by excessive growth prenatally and postnatally, a large dolichocephalic (elongated) head, distinctive facial configuration, and a non-progressive neurological disorder with intellectual disability. Advanced bone age is present in approximately 75 to 85% of patients.
The main clinical finding is prenatal and postnatal overgrowth. The growth velocity is particularly excessive in the first 3 to 4 years of life and subsequently proceeds at the normal rate, but in the high percentiles. The mean height is usually 2 to 3 years ahead of peers during childhood. The weight is usually appropriate for the height and the bone age is advanced by 2 to 4 years over chronological age, during childhood. Adult height usually exceeds the average of normal men or women. Some individuals may reach excessive adult heights; males of 193 cm to 203 cm (6 ft 4 in to 6 ft 8 in) and females up to 188 cm (6 ft 2 in) are known.
The craniofacial configuration is most characteristic, with a prominent forehead and receding forehead hairline in 96% of the cases, dolichocephalic (elongated) large head, widely spaced eyes (hypertelorism), down slanting of the eye lids and folds (palpebral features), high narrow palate, pointed chin, a long narrow face and a head shape that is similar to an inverted pear. The typical facial features are most apparent in childhood. As the child matures, the chin becomes more prominent and square in shape. In adults, the craniofacial characteristics are less distinctive but the chin is prominent and the large elongated head (dolicocephaly) and receding hairline (frontal bossing) remain.
Central nervous system manifestations are frequent. Delay in the attainment of milestones of development, walking and talking and in particular speech, is almost always present and clumsiness is frequent (60 to 80%), as is low muscle tone (hypotonia) and lax joints. Intellectual disability is present in 80 to 85% of the patients, with an average IQ of 72 and a range from 40 to borderline mild intellectual disability. Fifteen to 20% may have normal intelligence. Seizures may occur in 30% of those affected.
Individuals with Sotos syndrome can also experience behavioral problems at all ages that can make it difficult for them to develop relationships with others.
Newborns often have jaundice, difficulty feeding and low muscle tone (hypotonia). Heart defects are present in about 20% of children with Sotos syndrome but are usually not severe. Abnormalities in the genital and/or urinary systems occur in about 20% of affected individuals. Other findings associated with Sotos syndrome include conductive hearing loss that may be associated with an increased frequency of upper respiratory infections, eye abnormalities such as crossed eyes (strabismus), and skeletal problems. A curved spine (scoliosis) is present in about 40% of those affected but is usually not severe enough to require bracing or surgery. Premature eruption of teeth occurs in 60 to 80%. Approximately 2.2 to 3.9% of patients develop tumors including sacrococcygeal teratoma, neuroblastoma, presacral ganglioma and acute lymphoblastic leukemia.
Affected infants and children usually experience a delay in achieving certain developmental milestones (e.g., sitting, crawling, walking, etc.). They may not begin to walk until approximately 15 to 17 months of age. Affected children may also experience difficulty performing certain tasks requiring coordination (such as riding a bicycle or playing sports), fine motor skills (e.g., the ability to grasp small objects), and may demonstrate unusual clumsiness. Children with this disorder typically experience delays in attaining language skills. In many cases, affected children may not begin to speak until approximately two to three years of age.
Sotos syndrome is caused by an abnormality (mutation) in the NSD1 gene located in chromosome 5q35.2-q35.3. This is the only gene that has been associated with Sotos syndrome and an abnormality in this gene has been identified in approximately 80-90% of affected individuals.
Sotos syndrome is an autosomal dominant genetic condition. Dominant genetic disorders occur when only a single copy of an abnormal gene is necessary for the appearance of the disease. The abnormal gene can be inherited from either parent, or can be the result of a new mutation (gene change) in the affected individual. The risk of passing the abnormal gene from affected parent to offspring is 50% for each pregnancy regardless of the sex of the resulting child. Most people with Sotos syndrome have the NSD1 mutation as the result of a new mutation that was not inherited from a parent. When the parents are unaffected, the risk of having another child with the syndrome is very low (<1%).
The symptoms of Sotos syndrome can vary from person to person, even when they have the same NSD1 gene mutation. The genetic studies in affected patients have confirmed that the main characteristics of the syndrome are the large elongated head (dolicocephaly), the distinctive facial configuration, excessive growth and a non-progressive neurological disorder with intellectual disability.
Sotos syndrome affects males and females in equal numbers. This condition occurs in about one in 14,000 live births.
Symptoms of the following disorders may be similar to those of Sotos syndrome. Comparisons may be useful for a differential diagnosis.
Weaver syndrome, also known as Weaver-Smith syndrome, is an extremely rare disorder characterized by accelerated growth. Affected individuals have a particular facial appearance that is similar to Sotos syndrome in that a high broad forehead is often present, but the face is usually round in shape (not elongated) with widely spaced eyes (ocular hypertelorism) and an abnormally small jaw. Children often have increased muscle tone (hypertonia) and joint problems. (For more information on this disorder, choose "Weaver" as your search term in the Rare Disease Database.)
Beckwith-Wiedemann syndrome is a rare inherited disorder characterized by overgrowth, an abnormally large tongue (macroglossia), abnormal creases on the earlobes, protrusion of part of the intestines through an abnormal opening in the muscular abdominal wall near the umbilical cord (omphalocele) and abnormal enlargement of certain abdominal organs (visceromegaly) such as the liver, kidney, and/or pancreas and hypoglycemia (low blood glucose) early in life. Most individuals with Beckwith-Wiedemann syndrome have an abnormality in one of several genes located on the number 11 chromosome. Molecular genetic testing can help to determine the proper treatment for these patients. (For more information on this disorder, choose "Beckwith Wiedemann" as your search term in the Rare Disease Database.)
Simpson dysmorphia syndrome, also known as Simpson-Golabi-Behmel syndrome, is an X-linked recessive genetic disorder characterized by overgrowth before and after birth, a particular facial appearance that is different from Sotos syndrome, extra fingers and toes, extra nipples, separation of muscles in the abdominal wall (diastasis recti), and a skeletal abnormality in which the chest bone is depressed (pectus excavatum). (For more information on this disorder, choose "Simpson dysmorphia" as your search term in the Rare Disease Database.)
Fragile X syndrome is a genetic disorder caused by an abnormality in a gene on the X chromosome. The disorder occurs more frequently in males and as characterized by intellectual disability, language delays, behavioral problems, autism or autistic-like behavior (including poor eye contact and hand-flapping), enlarged external genitalia (macroorchidism), large or prominent ears, hyperactivity, delayed motor development and/or poor sensory skills. Affected individuals may also have an abnormally increased growth rate before puberty. Molecular genetic testing can differentiate fragile X syndrome from Sotos syndrome. (For more information on this disorder, choose "fragile X" as your search term in the Rare Disease Database.)
Several chromosomal abnormalities have been associated with symptoms that are similar to those of Sotos syndrome. Routine chromosome analysis can identify these abnormalities.
The diagnosis of Sotos syndrome is based on clinical grounds. The diagnosis can be confirmed by molecular genetic testing for NSD1 gene mutations. Some affected individuals have an NSD1 mutation in which a microdeletion is present that can be detected by a special type of chromosomal analysis called FISH (fluorescent in-situ hybridization). Rarely, affected individuals have a chromosome abnormality involving a rearrangement (translocation) in the number 5 chromosome.
Prenatal diagnosis for Sotos syndrome is available by DNA analysis obtained from fetal cells by amniocentesis or chorionic villus sampling if a specific NSD1 mutation has been identified in an affected family member.
The treatment of Sotos syndrome is directed toward the specific symptoms that are apparent in each individual. Treatment may require the coordinated efforts of a team of specialists. Pediatricians, pediatric endocrinologists, geneticists, neurologists, surgeons, speech pathologists, specialists who diagnose and treat skeletal disorders (orthopedists), physicians who diagnose and treat eye disorders (ophthalmologists), physical therapists, and/or other health care professionals may need to systematically and comprehensively plan an affected child's treatment.
When a child is diagnosed with Sotos syndrome, a heart examination and kidney ultrasound should be performed and if abnormalities are identified an appropriate specialist should be consulted. Children with Sotos syndrome should have a thorough examination every one to two years that includes a back exam for scoliosis, eye exam, blood pressure measurement, and a speech and language evaluation. Appropriate specialists should be consulted as needed.
Clinical evaluation should be conducted early in development and on a continuing basis to help confirm the presence and extent of developmental delay, psychomotor retardation, and/or intellectual disability. Such evaluation and early intervention may help ensure that appropriate steps are taken to help affected individuals reach their highest potential. Special services that may be beneficial to affected children may include infant stimulation, special education, special social support, physical therapy, occupational therapy, speech therapy, and adaptive physical education.
A small percentage (2.2 to 3.9%) of individuals with Sotos syndrome may be more prone to developing certain benign tumors and malignancies than the general population. Owing to the low risk for these problems, routine screening is not necessary.
Genetic counseling is beneficial for affected individuals and their families.
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Tatton-Brown K, Douglas J, Coleman K, et al. Childhood Overgrowth Collaboration: Genotype-phenotype associations in Sotos syndrome: an analysis of 266 individuals with NSD1 aberrations. Am J Hum Genet. 2005;77(2):193-204.
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Kurotaki N, Imaizumi K, Harada N, et al.: Haploinsufficiency of NSD1 causes Sotos syndrome. Nat Genet. 2002;30(4):365-366.
Cole TR, et al. Sotos syndrome: a study of the diagnostic criteria and natural history. J Med Genet. 1994;31(1):20-32.
Sotos JF, Dodge PR, Muirhead D, et al. Cerebral gigantism in childhood: a syndrome of excessively rapid growth and acromegalic features and a nonprogressive neural disorder. N Engl J Med. 1964;271:109-116.
Online Mendelian Inheritance in Man (OMIM). The Johns Hopkins University. Sotos Syndrome. Entry No: 117550. Last Edited July 22, 2011. Available at: http://www.ncbi.nlm.nih.gov/omim/. Accessed April 24, 2012.
Report last updated: 2012/04/26 00:00:00 GMT+0