Cystic fibrosis newborn screening: a model for neuromuscular disease screening?

Congenital neuromuscular disorders, such as Duchenne muscular dystrophy (DMD), spinal muscular atrophy (SMA), and Pompe disease (acid maltase deficiency [AMD]), are candidates for universal newborn screening (NBS). In this article, we discuss the future path of NBS for these disorders with particular emphasis on DMD NBS, because of the likely approval of new gene-modifying treatments, the possible benefits of earlier treatment with corticosteroids, and the recently demonstrated feasibility of a 2-tiered approach to NBS with screening by creatine kinase (CK) levels in dried blood spots followed by mutation detection in those with elevated CK. The cystic fibrosis (CF) NBS program is a successful model for NBS. CF outcomes have consistently improved into adulthood following introduction of CF NBS because considerable resources have been devoted to practices that include: attention to improving laboratory screening, consistent confirmatory testing and immediate referral of all newly diagnosed infants to designated CF care centers that follow established practice guidelines, and ongoing evaluation of CF care centers via a centralized clinical database. Like CF, DMD, SMA, and infantile AMD are inexorably debilitating and require lifetime multidisciplinary clinical management. NBS would address the delays in diagnosis that prevent patients from receiving timely treatments. Standardized care following early diagnosis would reduce disparities in clinical care and outcomes. NBS in these neuromuscular disorders should be implemented, utilizing lessons learned from the past 20 years of CF NBS: standardized protocols for all patients identified by DMD NBS, longitudinal follow-up in multidisciplinary clinics, and coordinated oversight of these clinics.

Restrictive lung involvement in facioscapulohumeral muscular dystrophy.

INTRODUCTION: Few studies have evaluated the frequency or predisposing factors for respiratory involvement in facioscapulohumeral muscular dystrophy type 1 (FSHD1) and type 2 (FSHD2). METHODS: We performed a prospective cross-sectional observational study of 61 genetically confirmed FSHD participants (53 FSHD1 and 8 FSHD2). Participants underwent bedside pulmonary function testing in sitting and supine positions, a standard clinical history and physical assessment, and manual muscle testing. RESULTS: Restrictive respiratory involvement was suggested in 9.8% (95% confidence interval 2.4-17.3): 7.5% FSHD1 and 25.0% FSHD2 (P = 0.17). Participants with testing suggestive of restrictive lung involvement (n = 6) were more severely affected (P = 0.005), had weaker hip flexion (P = 0.0007), and were more likely to use a wheelchair (P = 0.01). CONCLUSIONS: Restrictive respiratory involvement should be considered in all moderate to severely affected FSHD patients with proximal lower extremity weakness. The higher frequency of restrictive lung disease in FSHD2 seen here requires confirmation in a larger cohort of FSHD2 patients.

Can outcomes in Duchenne muscular dystrophy be improved by public reporting of data?

OBJECTIVE: To review current approaches for obtaining patient data in Duchenne muscular dystrophy (DMD) and consider how monitoring and comparing outcome measures across DMD clinics could facilitate standardized and improved patient care. METHODS: We reviewed annual standardized data from cystic fibrosis (CF) clinics and DMD care guidelines and consensus statements; compared current approaches to obtain DMD patient data and outcome measures; and considered the best method for implementing public reporting of outcomes, to drive improvements in health care delivery. RESULTS: Current methods to monitor DMD patient information (MD STARnet, DuchenneConnect, and TREAT-NMD) do not yet provide patients with comparative outcome data. The CF patient registry allows for reporting of standard outcomes across clinics and is associated with improved CF outcomes. A similar patient registry is under development for the Muscular Dystrophy Association (MDA) clinic network. Suggested metrics for quality care include molecular diagnosis, ambulatory status and age at loss of ambulation, age requiring ventilator support, and survival. CONCLUSIONS: CF longevity has increased by almost 33% from 1986 to 2010, in part due to a CF patient registry that has been stratified by individual care centers since 1999, and publically available since 2006. Implementation of outcome reporting for MDA clinics might promote a similar benefit to patients with DMD.

Linkage of large-vessel carotid atherosclerotic stroke to inflammatory genes via a systematic screen.

BACKGROUND: Inflammatory cytokines including the IL-1 family, TNF-alpha and IL-6 mediate the formation of thrombosis on the luminal surface of atherosclerotic plaques. Gene polymorphisms that regulate these cytokines' expression may explain part of the variation in susceptibility to stroke in patients with carotid atherosclerosis. The aim of this study was to evaluate the role of single-nucleotide polymorphisms (SNPs) and haplotypes in inflammatory genes as they relate to symptomatic carotid atherosclerosis. METHODS: The study included 95 subjects with symptomatic (transient ischaemic attacks or stroke) and 113 subjects with asymptomatic carotid atherosclerotic disease. A panel of evenly spaced SNPs including previously reported functionally significant polymorphisms were genotyped for IL-1beta (10 SNPs), IL-1alpha (nine SNPs), IL-1RN (11 SNPs), IL-6 (seven SNPs) and TNF-alpha and TNF-beta (seven SNPs). RESULTS: Using single SNP analysis, IL-1RN rs315934 (P=0.025), IL-1RN rs315946 (P=0.042), IL-1RN rs315921 (P=0.035), IL-6 rs1180243 (P=0.018) and IL-1alpha rs2071373 (P=0.025) were associated with decreased odds of symptomatic carotid disease. Additionally, two diplotypes of the IL-1RN gene (P=0.023 and 0.0064) and one diplotype in the IL-1alpha gene (P=0.02) were associated with a protective affect from cerebral ischaemic events. Logistic analysis for interaction of the protective SNPs reveals an additive effect of all SNP pair combinations. CONCLUSION: These results suggest that genetic polymorphisms in proinflammatory genes may contribute to interindividual differences in the development of symptomatic carotid atherosclerotic disease.

Gene expression profiling of lymphoblasts from autistic and nonaffected sib pairs: altered pathways in neuronal development and steroid biosynthesis.

Despite the identification of numerous autism susceptibility genes, the pathobiology of autism remains unknown. The present "case-control" study takes a global approach to understanding the molecular basis of autism spectrum disorders based upon large-scale gene expression profiling. DNA microarray analyses were conducted on lymphoblastoid cell lines from over 20 sib pairs in which one sibling had a diagnosis of autism and the other was not affected in order to identify biochemical and signaling pathways which are differentially regulated in cells from autistic and nonautistic siblings. Bioinformatics and gene ontological analyses of the data implicate genes which are involved in nervous system development, inflammation, and cytoskeletal organization, in addition to genes which may be relevant to gastrointestinal or other physiological symptoms often associated with autism. Moreover, the data further suggests that these processes may be modulated by cholesterol/steroid metabolism, especially at the level of androgenic hormones. Elevation of male hormones, in turn, has been suggested as a possible factor influencing susceptibility to autism, which affects approximately 4 times as many males as females. Preliminary metabolic profiling of steroid hormones in lymphoblastoid cell lines from several pairs of siblings reveals higher levels of testosterone in the autistic sibling, which is consistent with the increased expression of two genes involved in the steroidogenesis pathway. Global gene expression profiling of cultured cells from ASD probands thus serves as a window to underlying metabolic and signaling deficits that may be relevant to the pathobiology of autism.

A clinical genetic method to identify mechanisms by which pain causes depression and anxiety.

BACKGROUND: Pain patients are often depressed and anxious, and benefit less from psychotropic drugs than pain-free patients. We hypothesize that this partial resistance is due to the unique neurochemical contribution to mood by afferent pain projections through the spino-parabrachial-hypothalamic-amygdalar systems and their projections to other mood-mediating systems. New psychotropic drugs for pain patients might target molecules in such brain systems. We propose a method to prioritize molecular targets by studying polymorphic genes in cohorts of patients undergoing surgical procedures associated with a variable pain relief response. We seek molecules that show a significant statistical interaction between (1) the amount of surgical pain relief, and (2) the alleles of the gene, on depression and anxiety during the first postoperative year. RESULTS: We collected DNA from 280 patients with sciatica due to a lumbar disc herniation, 162 treated surgically and 118 non-surgically, who had been followed for 10 years in the Maine Lumbar Spine Study, a large, prospective, observational study. In patients whose pain was reduced >25% by surgery, symptoms of depression and anxiety, assessed with the SF-36 Mental Health Scale, improved briskly at the first postoperative measurement. In patients with little or no surgical pain reduction, mood scores stayed about the same on average. There was large inter-individual variability at each level of residual pain. Polymorphisms in three pre-specified pain-mood candidate genes, catechol-O-methyl transferase (COMT), serotonin transporter, and brain-derived neurotrophic factor (BDNF) were not associated with late postoperative mood or with a pain-gene interaction on mood. Although the sample size did not provide enough power to persuasively search through a larger number of genes, an exploratory survey of 25 other genes provides illustrations of pain-gene interactions on postoperative mood--the mu opioid receptor for short-term effects of acute sciatica on mood, and the galanin-2 receptor for effects of unrelieved post-discectomy pain on mood one year after surgery. CONCLUSION: Genomic analysis of longitudinal studies of pain, depression, and anxiety in patients undergoing pain-relieving surgery may help to identify molecules through which pain alters mood. Detection of alleles with modest-sized effects will require larger cohorts.