American Journal of Medical Genetics 41:212-215 (1991)
Prevalence of Type I Spinal Muscular Atrophy in North Dakota Larry Burd, Sarah K. Short, John T. Martsolf, and Richard A. Nelson Child Evaluation and Treatment Program, Medical Center Rehabilitation Hospital & Clinics (L.B.), Departments of Neuroscience (L.B.), Pediatrics (L.B., J.T.M.), and Medical Genetics (J.T.M.), School of Medicine (S.K.S., R.A.N.), and Center for Teaching and Learning (L.B.), University of North Dakota, Grand Forks Clinical progression after symptom onset is rapid and the mean age of death is 7 months. Ninety-five percent of children with type I SMA are dead by 18 months. Males are reported to be more frequently affected with type I SMA [Pearn, 1973,19781.Concordance for type I SMA has been frequently recorded in several sets of identical twins and it has further been noted that consanguinity was about 8 times greater among the parents of children with type 1 SMA than among controls [Brandt, 19501. While the role of environmental factors would appear to be small, it is nonetheless observed that the concordance for the age of death in affected infants is high. Table I1 presents previous prevalence studies of KEY WORDS: Werdnig-Hoffmann disease, type I SMA. children, muscle disease Since no known prevalence studies for type I SMA have been published in the United States we utilized the North Dakota Epidemiologic Survey to establish the INTRODUCTION prevalence and incidence in North Dakota over an 8 year Type I spinal muscular atrophy (Werdnig-Hoffmann period. disease type 1)results from an autosomal recessive gene METHOD [Pearn, 1973; Emery, 19871. The spinal muscular atrophies (SMA) constitute the second most common group We reviewed the death certificates and matched birth of fatal recessive diseases after cystic fibrosis, with an certificates from the years 1980 to 1987 in North Daestimated gene frequency of .0063 and the carrier fre- kota, for each child coded as having a death from quency of 1 in 80 in the Caucasian population [Pearn, Werdnig-Hoffmannsyndrome or type 1spinal muscular 1973, 1978, 1983; Pearn and Wilson, 1973; Emery, atrophy. Each physician who signed a death certificate 19871. The SMAs can be delineated into 8 or more dis- was then contacted and asked to provide a copy of the tinct clinical syndromes. infant's medical record. Pearn has described the historical classification of this disorder and current diagnostic criteria [Pearn, 1973, RESULTS 1978; Pearn and Wilson, 19731. The diagnostic criteria We were able t o obtain medical records on 8 of the 14 for type 1SMA are onset at
Prevalence of Type I Spinal Muscular Atrophy in North Dakota Larry Burd, Sarah K. Short, John T. Martsolf, and Richard A. Nelson Child Evaluation and Treatment Program, Medical Center Rehabilitation Hospital & Clinics (L.B.), Departments of Neuroscience (L.B.), Pediatrics (L.B., J.T.M.), and Medical Genetics (J.T.M.), School of Medicine (S.K.S., R.A.N.), and Center for Teaching and Learning (L.B.), University of North Dakota, Grand Forks Clinical progression after symptom onset is rapid and the mean age of death is 7 months. Ninety-five percent of children with type I SMA are dead by 18 months. Males are reported to be more frequently affected with type I SMA [Pearn, 1973,19781.Concordance for type I SMA has been frequently recorded in several sets of identical twins and it has further been noted that consanguinity was about 8 times greater among the parents of children with type 1 SMA than among controls [Brandt, 19501. While the role of environmental factors would appear to be small, it is nonetheless observed that the concordance for the age of death in affected infants is high. Table I1 presents previous prevalence studies of KEY WORDS: Werdnig-Hoffmann disease, type I SMA. children, muscle disease Since no known prevalence studies for type I SMA have been published in the United States we utilized the North Dakota Epidemiologic Survey to establish the INTRODUCTION prevalence and incidence in North Dakota over an 8 year Type I spinal muscular atrophy (Werdnig-Hoffmann period. disease type 1)results from an autosomal recessive gene METHOD [Pearn, 1973; Emery, 19871. The spinal muscular atrophies (SMA) constitute the second most common group We reviewed the death certificates and matched birth of fatal recessive diseases after cystic fibrosis, with an certificates from the years 1980 to 1987 in North Daestimated gene frequency of .0063 and the carrier fre- kota, for each child coded as having a death from quency of 1 in 80 in the Caucasian population [Pearn, Werdnig-Hoffmannsyndrome or type 1spinal muscular 1973, 1978, 1983; Pearn and Wilson, 1973; Emery, atrophy. Each physician who signed a death certificate 19871. The SMAs can be delineated into 8 or more dis- was then contacted and asked to provide a copy of the tinct clinical syndromes. infant's medical record. Pearn has described the historical classification of this disorder and current diagnostic criteria [Pearn, 1973, RESULTS 1978; Pearn and Wilson, 19731. The diagnostic criteria We were able t o obtain medical records on 8 of the 14 for type 1SMA are onset at
