[CITATION][C] Epidemiology of tuberous sclerosis

JP Osborne, A Fryer, D Webb - … of the New York Academy of …, 1991 - Wiley Online Library
JP Osborne, A Fryer, D Webb
Annals of the New York Academy of Sciences, 1991Wiley Online Library
Tuberous sclerosis (TSC) is a serious disease characterized by formation of multiple
hamartomas. It is best known for cutaneous and neurologic abnormalities, and the earliest
patients reported with TSC were all mentally retarded. Dominant inheritance with a high
mutation rate was first demonstrated in 1935, but it has only slowly become apparent that
affected individuals may be of normal intelligence, may not have fits, and may have few. if
any, skin lesions. Most clinical reports concentrate on affected individuals seen because of …
Tuberous sclerosis (TSC) is a serious disease characterized by formation of multiple hamartomas. It is best known for cutaneous and neurologic abnormalities, and the earliest patients reported with TSC were all mentally retarded. Dominant inheritance with a high mutation rate was first demonstrated in 1935, but it has only slowly become apparent that affected individuals may be of normal intelligence, may not have fits, and may have few. if any, skin lesions. Most clinical reports concentrate on affected individuals seen because of medical complications, usually mental retardation and fits. Epidemiologic studies are therefore required to determine the frequency of this disorder and the prevalence of symptoms, signs, and complications. The need for this information is becoming more important as affected normal parents wish for accurate genetic counseling. Indirect methods of estimated incidence were used by Gunther and Penrose] in 1935, who found the prevalence of TSC in hospitals for the mentally handicapped to be 1 in 300. The frequency of mental handicap in the population they studied was I%, and they therefore estimated the overall prevalence of TSC to be 1 in 30,000. A similar study? in Poland in 1968 gave an estimate of I in 23,000. The first proper epidemiologic survey was undertaken in 1968 in the Oxford Region, United Kingdom, when a prevalence of 1 in 100,000 was f0und. j More recently, prevalence was reestimated in the Oxford Region by Hunt and Lindenbaum4 who found a prevalence of I in 29,000 for persons under 65 years of age. They also identified an increased prevalence in the younger age groups-I in 20,000 for those below 30 years of age and 1 in 15,000 for those below 5 years of age. They estimated a possible birth incidence as high as I in 10.000. In Rochester, Minnesota, a study'over a 30-year period but in a small population gave a prevalence of I in 10,000. More recently a large study from the West of Scotland6 found a prevalence of 1 in 27,000 overall, but 1 in 12.000 for those aged less than 10 years. These data combine to suggest a possible birth incidence of I in 10,000. The only study of any size to report the frequency of mental retardation was that from Oxford in 19844 in which 68% of affected individuals had mild or severe retardation. All 10 affected individuals under the age of 5 were mentally handicapped. The incidence of seizures in those who are not mentally handicapped has not been reported. Several studies estimate the number of cases that appear to represent new mutations, giving figures ranging between 50 and 75%;. The clinical features of TSC have not been reported in any of these studies. We have been studying the population resident within the three Bristol Health Districts and seven of the Health Districts within the Wessex Regional Health Authority, and we have attempted to obtain complete ascertainment of patients affected by TSC. All the patients included in the study were examined by us (either AF or JPO) to ensure that they fulfilled accepted diagnostic criteria for TSC.'The study continues, but this paper reports the information obtained so far. a To whom correspondence 5hould be addressed.
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