Classification of spinal muscular atrophies

Evidence for compound heterozygosity causing mild and severe forms of autosomal recessive spinal muscular atrophy

Spinal muscular atrophy is an autosomal recessive disease of motor neurone degeneration which shows a variable phenotype. Two candidate genes show deletions in affected subjects but with no distinction between different forms of the disease. We report an unusual family in which mild and severe SMA coexists and patients are deleted for the SMN gene. The father is affected with late onset SMA; therefore this family shows pseudodominant inheritance. When typed using closely linked flanking markers the severely affected son does not share the same haplotype as his sib, who is deleted for SMN but shows no signs yet of SMA. This supports the hypothesis that differences in SMA phenotype can be explained by a multiple allele model.

Spinal muscular atrophy type II (intermediary) and III (Kugelberg-Welander). Evolution of 50 patients with physiotherapy and hydrotherapy in a swimming pool

We added hydrotherapy to 50 patients with spinal muscular atrophy (SMA) who were being treated with individual conventional physiotherapy. Hydrotherapy performed at an approximate temperature of 30 degrees Celsius, twice a week, for thirty minutes in children and forty-five minutes in adults during a 2-year period. The outcome derived from this combined modality of treatment was rated according to physiotherapeutic evaluations, the MMT (Manual Muscular Test), and the Barthel Ladder. Patients were reevaluated at 2-month intervals. After two years of ongoing treatment, we were able to observe that the deformities in hip, knee and foot were progressive in all SMA Type II patients, and in some Type III. Muscle strength stabilized in most SMA Type III patients, and improved in some. MMT was not done in SMA Type II. In all patients we were able to detect an improvement in the Barthel Ladder scale. This study suggests that a measurable improvement in the quality of daily living may be obtained in patients with SMA Types II and III subjected to conventional physiotherapy when associated with hydrotherapy.

Cataracts, motor system disorder, short stature, learning difficulties, and skeletal abnormalities: a new syndrome?

We present a 4-generation family in which affected individuals have cataracts, a motor neuronopathy with upper motor neuron signs, short stature, developmental delay, and skeletal abnormalities. An additional symptom is weakness during pregnancy which resolves after delivery. The condition is inherited in an autosomal dominant manner. The manifestations and inheritance are not found in any previously described conditions. We consider that this is a new syndrome.

Deletions in the SMN gene in infantile and adult spinal muscular atrophy patients from the same family

Recently, a gene determining spinal muscular atrophy (SMA), termed survival motor neuron (SMN) gene, has been isolated from the 5q13 region. This gene has been found to be deleted in most patients with childhood-onset SMA. We have studied the SMN gene in a clinically heterogeneous family, including one patient affected by infantile chronic SMA and three subjects with mild adult-onset muscle weakness. Deletions in the SMN gene were detected in all of these patients, indicating that the childhood and adult SMAs are genetically homogeneous in this family. Genotyping of the family members established that the three mildly affected individuals were homozygous for the same haplotype from the SMA region, whereas the more severely affected patient was heterozygous with one different haplotype.

Molecular analysis of the SMN and NAIP genes in Spanish spinal muscular atrophy (SMA) families and correlation between number of copies of cBCD541 and SMA phenotype

Spinal muscular atrophy is an autosomal recessive disorder which affects about 1 in 10,000 individuals. The three clinical forms of SMA were mapped to the 5q13 region. Three candidate genes have been isolated and shown to be deleted in SMA patients: the Survival Motor Neuron gene (SMN), the Neuronal Apoptosis Inhibitory Protein gene (NAIP) and the XS2G3 cDNA. In this report we present the molecular analysis of the SMN exons 7 and 8 and NAIP exon 5 in 65 Spanish SMA families. NAIP was mostly deleted in type I patients (67.9%) and SMN was deleted in 92.3% of patients with severe and milder forms. Most patients who lacked the NAIP gene also lacked the SMN gene, but we identified one type II patient deleted for NAIP exon 5 but not for SMN exons 7 and 8. Two other patients carried deletions of NAIP exon 5 and SMN exon 7 but retained the SMN exon 8. Three polymorphic variants from the SMN gene, showing changes on the sequence of the centromeric (cBCD541) and telomeric copies of the SMN gene, were found. In addition, we show several genetic rearrangements of the telomeric SMN gene, which include duplication of this gene in one normal chromosome, and putative gene conversion events in affected and normal chromosomes. Altogether these results corroborate the high genetic variability of the SMA region. Finally, we have determined the ratio between the number of centromeric and telomeric copies of the SMN gene in parents of SMA patients, showing that the majority of parents of types II and III patients carried three or more copies of the cBCD541 gene; we suggest a relationship between the number of copies of cBCD541 and the disease phenotype.

Gene deletions in spinal muscular atrophy

Two candidate genes (NAIP and SMN) have recently been reported for childhood onset spinal muscular atrophy (SMA). Although affected subjects show deletions of these genes, these deletions can lead to either a very mild or a severe phenotype. We have analysed a large number of clinically well defined patients, carriers, and normal controls to assess the frequency and extent of deletions encompassing both of these genes. A genotype analysis indicates that more extensive deletions are seen in the severe form of SMA than in the milder forms. In addition, 1 center dot 9% of phenotypically normal carriers are deleted for the NAIP gene; no carriers were deleted for the SMN gene. Our data suggest that deletions in both of these genes, using the currently available assays, are associated with both a severe and very mild phenotype.

Genetic homogeneity between childhood-onset and adult-onset autosomal recessive spinal muscular atrophy

Molecular diagnosis of childhood proximal spinal muscular atrophy has been enhanced by the discovery of the survival motor neuron (SMN) gene, which is absent or truncated in 98.6% of patients. To determine whether deletion analysis of the SMN gene may also be diagnostic for adult-onset disease, we studied six patients and found deletions in all. This finding will facilitate the diagnosis of adult-onset spinal muscular atrophy, and provides evidence for genetic homogeneity between the clinically diverse adult and childhood forms of the disease.

Neuromuscular disease: rehabilitation and electrodiagnosis. 2. Nerve disease

The purpose of this section of the Self-Directed Physiatric Education Program Study Guide on rehabilitation in diseases affecting nerve and muscle is to assist practitioners and trainees in physical medicine and rehabilitation by providing an overview of the evaluation, treatment, and rehabilitative care of patients with inherited and acquired neuropathies. Both diffuse and focal processes are discussed. Current research is briefly reviewed, and the utility and limitations of electrodiagnostic studies are discussed.

Expressed cadherin pseudogenes are localized to the critical region of the spinal muscular atrophy gene

Low-copy repeats have been associated with genomic rearrangements and have been implicated in the generation of mutations in several diseases. Here we characterize a subset of low-copy repeats in the spinal muscular atrophy (SMA) region in human chromosome 5q13. We show that this repeated sequence, named c41-cad, is a highly expressed pseudogene derived from an intact neuronal cadherin gene, Br-cadherin, situated on 5p13-14. Br-cadherin is expressed specifically in the brain, whereas the c41-cad transcripts are 10-15 times more abundant and are present in all tissues examined. We speculate that the c41-cad repeats, separately or in concert with other repeats in the SMA region, are involved in the pathogenesis of SMA by promoting rearrangements and deletions.

A novel cDNA detects homozygous microdeletions in greater than 50% of type I spinal muscular atrophy patients

Spinal muscular atrophy (SMA) is the second most common lethal, autosomal recessive disease in Caucasians (after cystic fibrosis). Childhood SMAs are divided into three groups (type I, II and III), which are allelic variants of the same locus in a region of approximately 850 kb in chromosome 5q12-q13, containing multiple copies of a novel, chromosome 5-specific repeat as well as many atypical pseudogenes. This has hampered the identification of candidate genes. We have identified several coding sequences unique to the SMA region. A genomic fragment detected by one cDNA is homozygously deleted in 17/29 (58%) of type I SMA patients. Of 235 unaffected individuals examined, only two showed the deletion and both are carriers of SMA. Our results suggest that deletion of at least part of this novel gene is directly related to the phenotype of SMA.

Fatty acid oxidation abnormalities in childhood-onset spinal muscular atrophy: primary or secondary defect(s)?

The purpose of this study was to further identify and quantify the fatty acid oxidation abnormalities in spinal muscular atrophy, correlate these with disease severity, and identify specific underlying defect(s). Fifteen children with spinal muscular atrophy (3 type I, 8 type II, 4 type III) were studied. Serum carnitine total/free ratios demonstrated a tendency toward an increased esterified fraction ranging 35-58% of total carnitine (normal: 25-30% of total) in younger children with types I and II. The remaining type II and III patients, older than 23 months of age at sampling, had normal esterified carnitine levels. Urinary organic acid analysis demonstrated mild to moderate medium-chain dicarboxylic aciduria in type I patients and normal, mild, or moderate increases in short-chain and medium-chain organic acids in type II patients. In the type III group, the organic acids were normal except for one patient with mild medium-chain dicarboxylic aciduria. Muscle intramitochondrial beta-oxidation was measured in 5 children (2 type I, 2 type II, and 1 type III) and a significant reduction in the activities of short-chain L-3-hydroxyacyl-CoA dehydrogenase, long-chain L-3-hydroxyacyl-CoA dehydrogenase, acetoacetyl-CoA thiolase, and 3-ketoacyl-CoA thiolase were found; however, normal crotonase activity was documented. Most strikingly, there was a marked increase (3- to 5-fold) in the activity ratios of crotonase to L-3-hydroxyacyl-CoA dehydrogenase and thiolase activities with both short- and long-chain substrates. The combined abnormalities suggest a defect in a mitochondrial multifunctional enzyme complex, distinct from the trifunctional enzyme. These abnormalities may be either primary or secondary and may respond to dietary measures to reduce the dependence on fatty acid oxidation.

Prenatal diagnosis of spinal muscular atrophy in Russia

Ninety-two families with spinal muscular atrophy (SMA) applied for genetic counselling and further prenatal diagnosis. To minimize expenses, only one tightly linked informative marker was determined in the course of preliminary examination, and non-radioactive allele detection was preferably used. Four prenatal diagnoses of SMA type I, four of SMA type II, and one of SMA type III were made. This trial programme shows the considerable requirements, importance, and potential effectiveness of prenatal prediction of SMA in Russia.

Autosomal recessive proximal spinal muscular atrophy in 101 sibs out of 48 families: clinical picture, influence of gender, and genetic implications

We analysed the clinical picture of 101 sibs (43 sib pairs, 5 triplets) with autosomal recessive proximal spinal muscular atrophy (SMA). Linkage data of 20 sibships, which were available for analysis, were in agreement with chromosome 5q linkage. The patients were classified according to the motor development into SMA I (never sat), SMA II (sitting without support), and SMA III (walking without aids). Three sibs with adult onset (> 30 years = SMA IV) were discussed as a separate entity. Age-of-onset of the 101 patients showed a wide spectrum (prenatal to 47 years). Among sib pairs with SMA I and SMA II the ages-of-onset appeared to be very similar except of one atypically discordant sib pair. With regard to SMA III, 3 out of 13 sibships (23%) showed a marked variation in age-of-onset ranging from 5-15 years within a family. Concerning acquired motor development (ability to sit and walk), 7 sibships (15%) belonged to different SMA types. Ages of death in 29 sib pairs in whom at least one sib had died before the age of 20 years were strikingly discordant. Neither the degree of disability nor the respiratory deficits are reliable predictors of life expectancy. Although a predominance of males can be observed, no significant effect of gender has been established in familial cases. The existence of multiple allelism seems to be the most suitable explanation for the high interfamilial variability considering the clinical concordance in most affected sib pairs.

Linkage study of chronic childhood-onset spinal muscular atrophy (SMA): confirmation of close linkage to D5S39 in French Canadian families

Chronic childhood-onset spinal muscular atrophy (SMA) is, after Duchenne muscular dystrophy, the most common neuromuscular disorder in childhood. Recent linkage analyses have mapped this disease to 5q12-5q14. We show that chronic SMA (Types II and III) is tightly linked to the marker locus D5S39 (Zmax = 5.47 at theta = 0.02) in eight French Canadian families. In contrast to previously published results, we do not observe close linkage between chronic SMA and D5S6 (Zmax = 0.34 at theta = 0.18) or D5S78 (Zmax = 0.25 at theta = 0.21). Last, we present a family that appears to be discordant for this localization but may represent the first example of an incompletely penetrant individual.

Prenatal prediction of Werdnig-Hoffmann disease using linked polymorphic DNA probes

Werdnig-Hoffmann disease is a common autosomal recessive neuromuscular disorder that results in paralysis and death. No treatment to prevent this disease or to alter its unremitting course has been found. Recently, linkage analysis with cloned DNA probes has shown that the mutation causing Werdnig-Hoffmann disease is located on chromosome 5q12-q14. We performed genetic analysis for the prenatal diagnosis of Werdnig-Hoffmann disease in seven at risk families. Two fetuses were diagnosed as being affected and the remainder as unaffected, and this was confirmed after birth. This study shows that prenatal diagnosis of Werdnig-Hoffmann disease has become feasible.

Werdnig Hoffman's disease (spinal muscular atrophy type I): A clinical study of 25 Saudi nationals in Al-Khobar

We describe the clinical features of 25 cases of Werdnig Hoffman's disease (spinal muscular atrophy (SMA) type I) seen propectively over a two-year period at the King Fahd Hospital of the University (KFHU), Al-Khobar. The hospital incidence rate was 1.93 per 1,000 live births (95% confidence limits, 0.80-3.06/1,000). The estimated prevalence rate for the community was 0.92/10,000 with 0.59-1.25 per 10,000 children as its 95% confidence limits. The male to female ratio was 2:3. Reduced fetal movements were reported by six mothers; 8 children (32%) had symptoms at birth, and 24 (96%) had symptoms by the time they were six months old. Other features apart from hypotonia, muscle weakness, and absent deep tendon reflexes included head lag with inability to achive head control at six months (88%), respiratory problems consisting of difficulty with breathing or frequent chest infections (44%), and difficulty with feeding (40%). Wasting with fisciculations of the tongue was seen in 64%. Death occurred within six months of presentation in 75% of the cases. The parents were consanguineous in 64% of the cases. This high consanguinity rate was probably the major cause for the high population prevalence rate.

Clinical variability of autosomal dominant spinal muscular atrophy

Autosomal dominant spinal muscular atrophy (SMA) is generally classified into a juvenile and an adult onset form. Clinical data of 20 affected members out of 6 families with autosomal dominant proximal SMA are reported. Three families could largely be classified as the adult onset form (onset after 20 years of life). They showed a benign course, most of them remaining ambulatory 10-40 years after clinical onset. Intrafamilial variability of onset was small, the progression of weakness within one family appeared to be very similar. Three patients of the other 3 families suffered from the juvenile onset form (first symptoms before the age of 12 years) with walking difficulties throughout life, whereas other family members would have been classified as adult onset SMA. The latter had an onset between age 17 and 28 years, and were only moderately handicapped when last examined (aged 38-60 years). The great intrafamilial variability in at least some of the families with autosomal dominant SMA is not compatible with the distinction of two clinically defined genetic entities. This observation is important with respect to a reliable prediction in clinical practice and genetic counselling.

A predominantly cervical form of spinal muscular atrophy

Clinical heterogeneity within the group of spinal muscular atrophies (SMA) in children can pose practical problems of diagnosis, prognosis and genetic counselling. In addition to the classic forms, unusual cases have been described. Five children with an atypical type of SMA are reported, characterised by early involvement of cervical muscles contrasting with initially mild or absent affection of peripheral muscles. Secondary involvement of respiratory muscles was responsible for the death of three children in the second to fourth year. The disorder may be recessively inherited.

Mapping of acute (type I) spinal muscular atrophy to chromosome 5q12-q14. The French Spinal Muscular Atrophy Investigators

Linkage analysis in twenty-five families with acute (type I) spinal muscular atrophy (SMA) showed that the mutant gene responsible for the disorder is tightly linked to the D5S39 locus. The mutation(s) causing the intermediate (type II) and juvenile chronic (type III) forms of SMA were also mapped to DNA marker D5S39 on chromosome 5 (5q12-q14). Thus, the three forms, which have been differentiated clinically on the basis of age of onset and clinical course, are most probably due to different mutations at a single locus on chromosome 5. Prenatal diagnosis of SMA type I will now be possible.

Population data on acute infantile and chronic childhood spinal muscular atrophy in Warsaw

This study provides epidemiological data on acute infantile (ASMA) and chronic childhood spinal (CSMA) muscular atrophy in Warsaw for the period 1976-1985. All calculations are based on the assumption that ASMA and CSMA result from mutations at two different gene loci. The incidence of ASMA and CSMA was 1 in 19474 live births with a corresponding gene and carrier frequency of 714 x 10(-5) and 1 in 70, respectively. The prevalence of CSMA for the year 1985 was 1.26 x 10(-5). These figures are higher than in similar studies in other countries. This fact might be connected with the careful ascertainment in this study.

Gene for chronic proximal spinal muscular atrophies maps to chromosome 5q

Proximal spinal muscular atrophies represent the second most common fatal, autosomal recessive disorder after cystic fibrosis. The childhood form is classically subdivided into three groups: acute Werdnig-Hoffmann (type I), intermediate Werdnig-Hoffmann disease (type II) and Kugelberg-Welander disease (type III). These different clinical forms have previously been attributed to either genetic heterogeneity or variable expression of different mutations at the same locus. Research has been hindered because the underlying biochemical defect is unknown, and there are insufficient large pedigrees with the most common and severe form (type I) available for study. Therefore, we have undertaken a genetic linkage analysis of the chronic forms of the disease (types II and III) as an initial step towards the ultimate goal of characterizing the gene(s) responsible for all three types. We report here the assignment of the locus for the chronic forms to the long arm of chromosome 5 (5q12-q14), with the anonymous DNA marker D5S39, in 24 multiplex families of distinct ethnic origin. Furthermore, no evidence for genetic heterogeneity was found for types II and III in our study, suggesting that these two forms are allelic disorders.

Electrocardiographic abnormalities in childhood spinal muscular atrophy

Tremors of the isoelectric line in routine electrocardiograms have been described in patients with spinal muscular atrophy and have been interpreted as fasciculations of denervated muscles. In order to evaluate this phenomenon, 13 patients with spinal muscular atrophy have been studied (average age: 37.3 months). A first electrocardiogram was recorded routinely; a second tracing was then recorded with double sensitivity and double speed. In addition, all patients were evaluated clinically and had M-mode and cross-sectional echocardiography. Regular and constant spikes on the isoelectric electrocardiographic line were recorded in 12 patients (93.4%); their frequency ranged from 39 to 48 cycles/sec (average: 42.08 +/- 2.64). Contrary to previous reports, we found an "abnormal" electrocardiogram in all our patients with severe spinal muscular atrophy. The only patient with a normal electrocardiogram had a mild and clinically stable form of spinal muscular atrophy. We did not find any significant structural cardiac abnormality by clinical and echocardiographic evaluation. We conclude that continuous tremor on the isoelectric line of electrocardiogram represents a characteristic of spinal muscular atrophy in these patients. It is a result of muscle fasciculations and does not imply any abnormality of the heart.

Distal infantile spinal muscular atrophy associated with paralysis of the diaphragm: a variant of infantile spinal muscular atrophy

We report the clinical, electrophysiological, and morphological observations of five infants with an unusual form of spinal muscular atrophy (SMA). In these infants muscular weakness and atrophy were initially restricted to the distal limbs and this pattern was associated with paralysis of the diaphragm. The difference between the clinical manifestations of this syndrome and the classical form of infantile spinal muscular atrophy (SMA type 1) as well as other congenital hereditary neuropathies is discussed.

Hereditary distal muscular atrophy with vocal cord paralysis and sensorineural hearing loss: a dominant form of spinal muscular atrophy?

In 1980 Young and Harper described a family with an unusual form of distal spinal muscular atrophy associated with vocal cord paralysis. We report a family with three similarly affected subjects. Progressive sensorineural hearing loss was an additional feature in our patients. Electrophysiological and histological investigations did not exclude an involvement of sensory neurones. Whether the classification of this dominant disorder with the spinal muscular atrophies is justified will depend on additional studies in further families.

A clinical, epidemiological and genetic study of hereditary motor neuropathies in Benghazi, Libya

A 4-year-search for spinal muscular atrophies (hereditary motor neuropathies, HMN) in Benghazi, Libya, yielded a total of 24 patients, among whom 18 were index cases. This group comprised 6 acute infantile, 12 chronic childhood, and 3 each with adult-onset proximal, and distal forms of the disorder. Distal HMN constituted 12.5% of the total cases. The crude average annual incidence of acute infantile HMN was 0.3/100,000 total population and 1/12,500 births in Benghazi. The crude prevalence rates of chronic childhood, adult-onset proximal, and distal types of HMN were 2.3, 0.6, and 0.6/100,000 respectively. The segregation ratios, 0.26 for acute infantile HMN and 0.24 for chronic childhood HMN, suggested autosomal recessive inheritance. The consanguinity rates among parents of cases and the population did not differ significantly.

Clinical-anatomic study of a family with bulbo-spinal muscular atrophy in adults

Four cases are presented, with bulbo-spinal muscular atrophy characterised by adult onset and rapid evolution. They belong to a family in which the type of inheritance is probably dominant. Two cases were studied histologically. The most striking feature was the disappearance of neurons in the lower motor nuclei of medulla and of the spinal anterior horns. An electron microscopic study was carried out in one case. Accumulation of neurofilaments was a general characteristic, in addition to the picture of different sized spheroids. The clinical-pathological relationship is discussed.

Neonatal spinal muscular atrophy presenting as respiratory distress: a clinical variant

Respiratory distress from diaphragmatic and intercostal muscular weakness was the presenting feature of two neonates with progressive spinal muscular atrophy, leading to death in the first 2 months of life. This atypical feature provides evidence of heterogeneity within the commonly used clarification of type 1 spinal muscular atrophy.

Clinical study of proximal spinal muscular atrophy. Report on 89 cases

A report on 89 cases of proximal Spinal Muscular Atrophy with observations on the clinical features, criteria of classification and modes of inheritance. The various forms into which SMA is divided probably represent a single disease that may begin at any age and may vary in severity, due, as a rule, to an autosomal recessive gene.

Late-childhood-onset spinal muscular atrophy in three Melanesian families in Papua New guinea

Late-childhood-onset spinal muscular atrophy (SMA) with rapid progression from proximal to distal muscle groups and leading to severe incapacity or death in adolescence or early adult life, was studied in two Melanesian families in Papua New Guinea. Probable SMA with cardiomyopathy was observed in a 12-year-old boy in a related family. The pattern of inheritance in the study group did not conform to any of the conventional Mendelian modes and it was conjectured that the disease was expressed in heterozygote carriers of the SMA gene only when an allelomorphic activator gene was present.

Succinic semialdehyde dehydrogenase deficiency

A coupled assay using [14C]4-aminobutyric acid and a direct assay using [14C]succinic semialdehyde have been designed to assay te activity of succinic semialdehyde dehydrogenase in a patient with 4-hydroxybutyric aciduria and family members. In the coupled assay less than 3% of control succinic semialdehyde dehydrogenase activity was found in lysates of lymphocytes isolated from whole blood of the patient. In the direct assay there was no detectable activity of the enzyme in lysates of isolated lymphocytes or cultured lymphoblasts. Results indicated the parents to be heterozygous carriers carriers of the abnormal gene, consistent with an autosomal recessive inheritance.

The discovery of neuronopathy and neuropathy as a cause of progressive paralysis in childhood. The historical origins of modern differential diagnosis in neuromuscular disease

The concept of the differential diagnosis has a central place in all clinical medicine. In neurology and paediatrics, evolution of thought concerning the differential diagnosis of the child presenting with symptoms of neuromuscular disease was far in advance of similar diagnostic approaches to problems of infectious, infective and neoplastic disease; and as such forms a significant historical model for the development of modern clinical approaches to the sick or disabled child. The account presented in this paper provides a detailed historical review of the development of thought relating to the causes of neuromuscular disease. Nosological developments concerning diseases of the motor unit can be conveniently classified into three periods: (a) a "state of the art" period to 1850; (b) 1850-1890 - a period of parallel and interdependent advances in both normal neuro-anatomy and neurophysiology, and diseases recognized as variations from such norms. In this era Duchenne was the first to write about the differential diagnosis of the progressive muscular paralysis in childhood; and Gowers was the first to write specifically on the hereditary transmission of this group of diseases; (c) in 1891 was described the first case of childhood neuronopathy recognized as such, and with this development was ushered in the modern era of clinical differential diagnosis of childhood neuromuscular disease. The "splitters" have won the great debate concerning the clinical approach to neurological diseases. The continual further refining of an exact diagnosis is the only way in which a realistic prognosis can be forecast, correct genetic counseling can be offered, and (if the condition is treatable) optimal therapy can be introduced.

Juvenile proximal spinal muscular atrophy with early hypertrophy of calves

The clinical, electrophysiological, histological and ultrastructural features of a patient with chronic spinal muscular atrophy of adolescent onset associated with hypertrophied calf-muscle are described. This recently recognised entity must be distinguished from other types of spinal muscular atrophy.

Juvenile spinal muscular atrophy: a new hexosaminidase deficiency phenotype

A 24-year-old Ashkenazi Jewish man was evaluated for a nine-year history of progressive leg weakness with fasciculations. Electromyography, nerve conduction velocities, muscle biopsy, and serum creatine kinase were consistent with anterior horn cell disease. On rectal biopsy, ganglion cells were filled with membranous cytoplasmic bodies and an unusual submucosal layer of periodic acid-Schiff positive histiocytes filled with granules was seen. Hexosaminidase A in serum and leukocytes was severely decreased in the patient and partially decreased in parents and a brother. A paternal relative had classic infantile Tay-Sachs disease. Juvenile spinal muscular atrophy in this patient, closely resembling the Kugelberg-Welander phenotype, resulted from an alpha-locus hexosaminidase deficiency disorder, possibly a genetic compound of HEX alpha 2 and a milder hexosaminidase alpha-locus allele. Other cases of hexosaminidase deficiency have included anterior horn cell disease as part of a more complex disorder, but this is the first case, to our knowledge, of a hexosaminidase deficiency disorder presenting as spinal muscular atrophy.

Rehabilitation in muscular dystrophy

This paper reviews the types of muscular dystrophy and then their management, considering the Duchenne form in some detail and then the special problems encountered with other types.