Abstract: Becker muscular dystrophy (BMD) is a milder form of X-linked Duchenne muscular dystrophy (DMD). Here, we report a study of 75 patients with immunoblot and/or immunostaining findings of muscle biopsy consistent with BMD (abnormal dystrophin). We utilized multiplex ligation dependent probe amplification (MLPA) on genomic DNA (gDNA) to screen all 79 exons for both deletions and duplications. A total of 19 patients testing negative for MLPA mutations were tested for mRNA splicing abnormalities using cDNA-MLPA on muscle biopsy. Complete cDNA sequencing was done on MLPA-negative patients. We identified disease-causing mutations in 66 (88%) of the patients. Of the mutation-positive patients, 42 (64%) showed deletions of one or more exons, 14 (21%) showed duplications, and 10 (15%) showed various mutations detected by cDNA-MLPA and sequencing studies. We found a high rate of "exceptions" to the reading frame rule in this BMD series (out-of-frame BMD; 17/56 deletions/duplications; 30%). This was partly explained by the high incidence of 5' gene deletions in BMD patients (a region known to be a hotspot for exceptions), and due to complex splicing patterns in which a subset of transcripts showed deletions larger than gDNA (exon-skipping). Comparing our findings in BMD to previously published DMD data, BMD patients have higher proportions of duplications, a different distribution of mutations, and higher exception to the reading frame rule.
Abstract: Dysferlin deficiency causes limb-girdle muscular dystrophy type 2B (LGMD2B; proximal weakness) and Miyoshi myopathy (distal weakness). Muscle inflammation is often present in dysferlin deficiency, and patients are frequently misdiagnosed as having polymyositis. Because monocytes normally express dysferlin, we hypothesized that monocyte/macrophage dysfunction in dysferlin-deficient patients might contribute to disease onset and progression. We therefore examined phagocytic activity, in the presence and absence of cytokines, in freshly isolated peripheral blood monocytes from LGMD2B patients and in the SJL dysferlin-deficient mouse model. Dysferlin-deficient monocytes showed increased phagocytic activity compared with control cells. siRNA-mediated inhibition of dysferlin expression in the J774 macrophage cell line resulted in significantly enhanced phagocytosis, both at baseline and in response to tumor necrosis factor-alpha. Immunohistochemical analysis revealed positive staining for several mononuclear cell activation markers in LGMD2B human muscle and SJL mouse muscle. SJL muscle showed strong up-regulation of endocytic proteins CIMPR, clathrin, and adaptin-alpha, and LGMD2B muscle exhibited decreased expression of decay accelerating factor, which was not dysferlin-specific. We further showed that expression levels of small Rho family GTPases RhoA, Rac1, and Cdc 42 were increased in dysferlin-deficient murine immune cells compared with control cells. Therefore, we hypothesize that mild myofiber damage in dysferlin-deficient muscle stimulates an inflammatory cascade that may initiate, exacerbate, and possibly perpetuate the underlying myofiber-specific dystrophic process.
Abstract: BACKGROUND: Spinal muscular atrophy (SMA) represents the second most common fatal autosomal recessive disorder after cystic fibrosis. Due to the high carrier frequency, the burden of this genetic disorder is very heavy in developing countries like India. As there is no cure or effective treatment, genetic counseling becomes very important in disease management. SMN1 dosage analysis results can be utilized for identifying carriers before offering prenatal diagnosis in the context of genetic counseling. METHODS: In the present study we analyzed the carrier status of parents and sibs of proven SMA patients. In addition, SMN1 copy number was determined in suspected SMA patients and parents of children with a clinical diagnosis of SMA. RESULTS: Twenty nine DNA samples were analyzed by quantitative PCR to determine the number of SMN1 gene copies present, and 17 of these were found to have one SMN1 gene copy. The parents of confirmed SMA patients were found to be obligate carriers of the disease. Dosage analysis was useful in ruling out clinical suspicion of SMA in four patients. In a family with history of a deceased floppy infant and two abortions, both parents were found to be carriers of SMA and prenatal diagnosis could be offered in future pregnancies. CONCLUSION: SMN1 copy number analysis is an important parameter for identification of couples at risk for having a child affected with SMA and reduces unwarranted prenatal diagnosis for SMA. The dosage analysis is also useful for the counseling of clinically suspected SMA with a negative diagnostic SMA test.
Abstract: BACKGROUND: Hirayama disease (HD) is a segmental nonprogressive spinal muscular atrophy found in male patients. OBJECTIVE: To report the results of a comprehensive evaluation of clinical, magnetic resonance imaging (MRI), electromyography (EMG), and survival motor neuron (SMN) gene analysis of HD. DESIGN: Clinical, MRI, and SMN gene deletion study. SETTING: Tertiary care teaching hospital. PATIENTS: Patients with HD diagnosed according to defined criteria were included in the study. INTERVENTIONS: Patients underwent a neurologic evaluation and pedigree charting. Concentric needle EMG was performed on a number of muscles. Motor nerve conduction study of the median, ulnar, and peroneal nerves and sensory conduction study of the median, ulnar, and sural nerves were also performed. Spinal MRI of the cervical region was performed with the 2-T scanner operating at 1.5 T. Gene deletion study of SMN1 and SMN2 was performed in all patients. MAIN OUTCOME MEASURES: History of trauma, occupation, exercise, associated medical disease, and cold paresis and muscle wasting, power, reflex changes, and tone. RESULTS: Fifteen male patients with HD from 14 families participated in the study (mean age at the onset of disease, 18 years; range, 15-23 years). Muscle weakness and wasting were noted in the right upper limb in 12 and the left upper limb in 3, which became bilateral in 8 patients. Cold paresis was present in 6 patients and polyminimyoclonus in all patients. The EMG revealed fibrillations in 10, fasciculations in 15, and neurogenic motor unit potentials in C7, C8, and T1 myotomes in all patients. The EMG abnormalities were unilateral in 5, bilateral in 10, and subclinical in 2 patients. Spinal MRI revealed cord atrophy in 3 of 11 patients. Although family history was present in 1 brother only, the results of both SMN1 and SMN2 gene deletion studies were negative in all patients. CONCLUSIONS: The SMN gene deletion is not found in HD. Exclusive occurrence in male patients and the presence of this disease in 2 brothers suggest a possible role of the X chromosome, which needs further evaluation.
Abstract: In view of the paucity of deletion studies of survival of motor neuron (SMN) and neuronal apoptosis inhibitor protein (NAIP) genes in Indian SMA patients, this study has been undertaken to determine the status of SMN1, SMN2 and NAIP gene deletions in Indian SMA patients. Clinically and neurophysiologically diagnosed SMA patients were included in the study. A gene deletion study was carried out in 45 proximal SMA patients and 50 controls of the same ethnic group. Both SMN1 and NAIP genes showed homozygous absence in 76% and 31% respectively in proximal SMA patients. It is proposed that the lower deletion frequency of SMN1 gene in Indian patients may be due to mutations present in other genes or population variation, which need further study.
Abstract: Spinal muscular atrophy has been classified into four groups based on the age of onset and clinical severity of the disease. Homozygous deletion in SMN1 gene causes the disease but the clinical severity may be modified by copy number of homologous gene SMN2 as well as the extent of deletion at SMN locus. In the view of scarcity of genotype and phenotype correlation data from India, this study has been undertaken to determine that correlation in SMA patients by using the SMN and NAIP genes and two polymorphic markers C212 and C272 located in this region. Two to four alleles of the markers C212 and C272 were observed in normal individuals. However, majority of Type I patients showed only one allele from both markers whereas in Type II and III patients, 2-3 alleles were observed. The SMN2 copy number in our type III patients showed that patients carry 3-5 copies of SMN2 gene. Our results suggest that extent of deletions encompassing H4F5, SMN1, NAIP and copy number of SMN2 gene can modify the SMA phenotype, thus accounting for the different clinical subtypes of the disease.
Abstract: OBJECTIVES: To study the psychosocial issues associated with prenatal diagnosis of SMA in India and the use of SMN1 copy number analysis for carrier detection prior to offering prenatal diagnosis. METHODS: Homozygous deletion of SMN1 gene was done by PCR-RFLP. Copy number analysis of SMN1 gene was performed by quantitative PCR. RESULTS: We report our experience of eight cases of prenatal diagnosis for SMA and the use of carrier detection prior to offering prenatal diagnosis. Quantitative PCR results show that SMN1 copy number analysis is useful to identify couples at risk. CONCLUSION: Case analyses depict unique psychosocial issues associated with prenatal diagnosis of SMA from India.
Abstract: AIMS: This study evaluates clinical, electromyography (EMG) and genetic analysis of consecutive patients with spinal muscular atrophy (SMA) in a tertiary care adult neurology practice in India. METHODS: Consecutive patients with SMA attending the neurology out patient department during 2001-2003 were included. They were subjected to a detailed clinical examination, nerve conduction and EMG and muscle biopsy. Clinically patients were classified into generalised and segmental SMA. SMN gene deletion study was carried out in all the patients. RESULTS: There were 15 patients with type III and type IV SMA and 15 with segmental SMA (Hirayama disease). The age ranged between 5 and 23 years in type III SMA, 33-50 years in type IV SMA and 16-30 years in Hirayama disease (HD). The latter was found exclusively in males. Family history was observed in 1 patient each in all the groups. In SMA III mother and brother were affected, in SMA IV two siblings and in HD one brother had similar disease. One type III SMA family was associated with deafness and one type IV family had strong association with maturity onset diabetes in young. The EMG was characterised by lack of fibrillations in all type III and IV SMA patients except 1 whereas in HD, 11 out of 15 had fibrillations suggesting ongoing denervation. The EMG was suggestive of reinnervation in generalised SMA in both upper and lower limb muscles where as these abnormalities were restricted to C7-T1 mytomes in HD. Muscle biopsy in 10 patients with generalised SMA revealed group atrophy in all, and loss of fascicular architecture in 3, clumping of nuclei in 7 and hypertrophic fibers in 4. SMN1 gene deletion was present in 3 patients with type III but none in type IV and HD. CONCLUSION: SMN gene deletion was positive in 33% type III SMA whereas it was negative in type IV and HD. Presence of HD only in males may be consistent with X-linked disorder.
Abstract: Azoospermia factor locus (AZF) is assumed to contain the genes responsible for spermatogenesis. Deletions in these genes are thought to be pathologically involved in some cases of male infertility associated with azoospermia or oligozoospermia. An attempt was made to establish the prevalence of micro-deletions on the Y chromosome in 79 infertile North Indians with azoospermia and oligozoospermia. Detail clinical examinations as well as endocrinological parameters were also done. Polymerase chain reaction (PCR) micro-deletion analysis was done in 79 infertile men. For this, genomic DNA was extracted from the peripheral blood. Seven sets of primers were used encompassing AZFa, AZFb and AZFc regions. Micro-deletions in five of the 79 cases (6.3%) showed deletions of at least one of the STS markers. Deletions were detected with known and unknown aetiology and at least in one of the infertile male with varicocele. AZF micro-deletions seen in idiopathic infertile males suggest the need for molecular screening in non-idiopathic cases.
Abstract: The reading frame hypothesis has been proposed to explain the molecular basis of two allelic forms of muscular dystrophies, Duchenne/Becker muscular dystrophy (D/BMD). To evaluate the hypothesis in Indian D/BMD patients, we analyzed deletion of dystrophin exons in 147 DMD and 19 BMD patients. Our studies showed deviation of more than 30% from the reading frame hypothesis in DMD patients (47/147). The present results implicate a need to reevaluate the reading frame hypothesis.
Abstract: Cancer is a major health problem worldwide which is likely to assume alarming proportions in the next two decades. Communication and information have increasingly been considered important in helping people to cope with cancer. The arrival of Internet offers the opportunity to fundamentally reinvent medicine and health care delivery. Medical professionals can now use the Internet for continuing medical education, access latest medical information, for fast confirmation of diagnosis, exchange opinion on treatment strategies and in palliative care. Internet can provide cost-effective and timely ways to deliver a complex mix of interesting and high-quality information and expertise to cancer patients. Patients can also independently search the Internet to know about their illness and treatment options. However, of concern is the quality of information that is available in the 'Net'. Some Internet sites may contain erroneous information on cancer and can pose serious problems. There are also many good sites, which provide quality information on cancer for medical professionals, researchers and patients. This article focuses on how the Internet will aid us in fight against cancer.
Abstract: The spinal muscular atrophies are a group of disorders characterized by flaccid limb weakness. It is necessary to differentiate these from other causes and identify the SMA variants. In classical SMA, majority of the patients shows homozygous deletion of the telomeric SMN gene (SMN1) on chromosome 5q. The availability of DNA analysis has allowed proper genetic counseling and prenatal diagnosis in the affected families. Application of newer techniques has enabled more accurate carrier detection. Our objective is to stress the variability in the clinical features and recent advances in the molecular diagnosis for SMA.
