Deletions in the spinal muscular atrophy gene region in a newborn with neuropathy and extreme generalized muscular weakness.

A newborn presented with respiratory insufficiency requiring artificial ventilation, inability to swallow, lack of spontaneous movements including the facial muscles, and areflexia. Nerve conduction velocities were not recordable. Molecular analysis showed a homozygous deletion in the spinal muscular atrophy (SMN) gene region on chromosome 5q. Pathological and neuropathological examination revealed a normal number of anterior horn cells, hypomyelinated axons in peripheral nerves and some atrophy of skeletal muscle fibres in combination with sarcoplasmic glycogen accumulation. This observation illustrates that severe congenital neuropathy can result from deletions in the SMN gene.     

Prenatal onset spinal muscular atrophy.

Five patients with severe spinal muscular atrophy (SMA) type I, all of whom presented with reduced fetal movements in utero, severe weakness at birth, and short survival time were assessed to attempt to determine whether their phenotype could be explained by their genotype. The diagnosis was confirmed by clinical, electrophysiological and histopathological features. Polymerase chain reaction assays were used to define the molecular diagnosis. A gene-dosage assay was used to assess the quantity of centromeric survival motor neuron gene (SMNc) present. In all cases the telomeric survival motor neuron gene (SMNt) was absent. The SMNc gene was present but in reduced copy number compared with a control group of children with less severe type I SMA, so may be important in determining severity. In the differential diagnosis of reduced fetal movements, SMA should be considered. The clinical classification may in future be clarified by molecular genetic findings.     

Infantile spinal muscular atrophy

Summary Seven cases of infantile spinal muscular atrophy are reported. In one child, mental retardation was associated with hypotonia. Similarity between Werdnig-Hoffmann’s disease and Oppenheim’s amyotonia congenita is stressed. The literature is briefly reviewed and the importance of muscle biopsy stressed. From The Department of Pediatrics, Govt. Medical College, Rohtak and Medical College, Patiala.     

小儿脊髓性肌萎缩

脊髓性肌萎缩是一组常染色体隐性(AR)遗传的进行性并通常为对称性肌无力与萎缩的疾病.5q型常见,由5q13 上SMNI基因缺失(95%的病例)或突变(约5%的病例)引起.分为4型.18个月内起病的Ⅰ型与Ⅱ型往往因呼吸吞咽不良、不能站坐走与继发骨折等而坝后严重.非-5q型为一组异源性运动神经元病,临床表现与前者有所不同.5q型的诊断根据病史、血清肌酶、肌电图、肌活检而确诊靠基因检查,如纯合子缺失用PCR-SSCP等检测、点突变用点突变序列检测.胎儿细胞基因检测可提供产前诊断.治疗是多方面的.对症治疗与支持治疗要求有关各科专家积极合作.随着医疗技术的进步.患者的寿命与活动状况均有改进.分子治疗已初露曙光.     

Diaphragmatic paralysis due to spinal muscular atrophy. An unrecognised cause of respiratory failure in infancy?

An unusual form of spinal muscular atrophy presenting with respiratory failure was observed in four infants from two families. In one, whose death was attributed to pneumonia, the diagnosis was inferred retrospectively after two siblings died from an identical illness and were shown to have diaphragmatic paralysis and the typical electrophysiological and histological features of spinal muscular atrophy. Other signs of skeletal muscular weakness were absent or inconspicuous. The fourth, unrelated infant presented in an identical way but has survived for over a year on a ventilator. Two months after the onset of respiratory paralysis, more extensive skeletal muscular weakness was seen. Other infants, dying of unexplained respiratory illness, may have this disorder and some may be included in the miscellany of disorders that constitute the sudden infant death syndrome.     

X-linked infantile spinal muscular atrophy

Four male infants from three sibships in an extended family were noted to have hypotonia, areflexia, and congenital joint contractures. The findings of electromyography and muscle histology were consistent with infantile spinal muscular atrophy (SMA). Pedigree analysis suggests that this disorder represents an X-linked, recessive form of SMA. Findings in similar kindreds may explain the previously reported increased male-female ratio in infantile SMA.     

婴儿型进行性脊肌萎缩症5例及1例家系调查

目的：探讨婴儿型进行性脊肌萎缩症的发病率及诊断治疗。方法：分析5例婴儿进行性脊肌萎缩症的临床特点及其中1例家系发病情况。结果：5例均为1岁以内患儿，男4例，女1例，1例家系中第2代姐弟5人中4人发病，父母均为隐性携带者。结论：本病1岁以内发病，进行性肌萎缩与无力，男多于女，为常染色体隐性遗传性疾病。     

Therapeutic advances in spinal muscular atrophy

Spinal muscular atrophy (SMA) is a rare neuromuscular condition, characterized by loss of motor neurons as a result of a mutation in the survival motor neuron gene. This results in muscle wasting and in the most common and severe type, death before 24 months. Over the recent years there has been a dynamic shift in the therapeutic options for these patients involving both clinical trials in genetic modifying therapies to indirectly improve the survival motor neuron protein level and hence strength, muscle promotor therapies, up/down regulation of modifier genes and more recently gene therapy to replace the mutated survival motor neuron gene. This review addresses the pathogenesis of SMA and the resultant therapeutic approaches as well as the current state in clinical trials and future development.     

Therapeutic advances in spinal muscular atrophy

Spinal muscular atrophy (SMA) is a rare neuromuscular condition, characterized by loss of motor neurons as a result of a mutation in the survival motor neuron gene. This results in muscle wasting and in the most common and severe type, death before 24 months. Over the recent years there has been a dynamic shift in the therapeutic options for these patients involving both approved therapies, including gene therapy, and access to clinical trials in genetic modifying therapies to indirectly improve the survival motor neuron protein level and hence strength, muscle promotor therapies, up/down regulation of modifier genes and SMN independent therapies. This review addresses the pathogenesis of SMA and the resultant therapies available as well as the current clinical trials and future development.     

Molecular diagnosis of spinal muscular atrophy

The frequency of deletions within the survival motor neurone (SMN) and neuronal apoptosis inhibitory protein (NAIP) genes in patients with spinal muscular atrophy (SMA), and the impact of this on the diagnosis and prenatal diagnosis of SMA, were investigated by molecular analysis of stored DNA and retrospective review of case notes. In type I SMA, 16 of 17 cases were homozygously deleted for exons 7 and 8 of SMN, 14 of 17 were homozygously deleted for exon 5 of NAIP, and 13 of 17 were deleted for both. In types II and III SMA, seven of nine cases were deleted for exons 7 and 8 of SMN. Deletions of SMN and NAIP occurred in four of nine cases. With one exception, the deletion genotypes of probands, affected siblings, and terminated fetuses were identical. Molecular studies are replacing conventional investigations for SMA and have a high uptake prenatally.

     

Hand and ECG tremor in spinal muscular atrophy.

The presence of hand and electrocardiogram (ECG) tremor was studied in 31 children with severe, intermediate, or mild form of spinal muscular atrophy. Clinical tremor of the hands was seen in 16 (59%) of 27 patients, all with benign forms of the disease. Nineteen patients had ECG tremors, of whom 17 had the mild or intermediate form. With the exception of one, all patients in the mild or intermediate group had hand or ECG tremor. Hand and ECG tremor are valuable in the diagnosis of the benign forms of spinal muscular atrophy; they are of no value in diagnosis of the severe infantile type.     

Respiratory management of the infant with type 1 spinal muscular atrophy.

A recent paper has highlighted the differences in the respiratory management offered to infants with type 1 spinal muscular atrophy (SMA-1). Current views appear polarised between those who would offer nothing, to those who would proceed as far even as tracheostomy and long term invasive ventilation for these infants. Here we offer a personal view, as a possible template for managing a vexed and emotional problem. The complex non-respiratory aspects of the holistic care of these infants will not be discussed.     

Long-term ventilatory support in spinal muscular atrophy

Before ethical issues regarding prolonging life in patients with degenerative disease can be considered, the quality of life with medical intervention must be delineated. We have followed 15 patients with spinal muscular atrophy who have been treated with mechanical ventilation. They have received assisted ventilation for an average of 8 years 10 months (range 5 months to 23 years 10 months). Three of the patients required full-time ventilator assistance at the time of initiation of ventilation; the remaining 12 used nighttime ventilation for an average of 8 years 7 months. Nine patients continue to receive nighttime ventilation only. Two patients died after 5 years and 14 years of assisted ventilation, respectively. Of the 10 patients more than 18 years of age, three graduated from college, two are in college, three graduated from high school, and two completed eleventh grade. One patient is a mother of a healthy child. Two patients are employed, and two others have found fulfilling volunteer work. Ventilator support has not significantly interfered with these patients' plans and expectations.     

脊髓性肌萎缩症1例报道

脊髓性肌萎缩症（spinal muscular atrophy,SMA）是一种常染色体隐性遗传病,是由于脊髓前角细胞变性导致的肌肉萎缩,研究表明其发病与SMN基因有关,国外报道发病率为1／6000～1／10000,携带者频率为1／40～1／60。现将我院门诊诊断的1例患儿报道如下,以期提高临床医师对该病的认识。     

婴儿脊髓性肌萎缩症3例报告

婴儿脊髓性肌萎缩症(SMA)是一种常染色体隐性遗传性疾病,病变主要表现在脊髓前角细胞的广泛脱失及变性,脑干的运动神经核常常受累.临床上易与脑性瘫痪混淆.我科于1996～1998年,收治146名瘫痪患者,其中诊断婴儿脊髓性肌萎缩症3例,占瘫痪病人的2%.为了提高临床医生对本病的认识、诊断及预后的判断,现报告如下.