Importance and challenge of making an early diagnosis in LMNA-related muscular dystrophy

OBJECTIVE

To identify the most useful clinical and histologic markers that facilitate early diagnosis in LMNA-related muscular dystrophy and to assess the usefulness of Western blotting (WB) for lamin A/C.

METHODS

We analyzed the clinical and histologic features and WB results of all patients with laminopathies diagnosed in a research-based diagnostic service over 8 years.

RESULTS

Although patients with congenital muscular dystrophy (MDCL) (n = 5) and Emery-Dreifuss muscular dystrophy (EDMD) (n = 5) had distinctive early clinical features, the lack of a suggestive clinical phenotype significantly delayed diagnosis in 2 of 3 patients with limb-girdle muscular dystrophy (LGMD) (n = 3). In addition, 6 of 20 muscle biopsy samples were considered nondystrophic, which contributed to delays in diagnosis in some patients. Neck extensor involvement (weakness or contractures) was the most consistent clinical sign, present in all patients. Reduced lamin A/C levels on WB were seen in 5 of 9 patients with laminopathies.

CONCLUSION

Clinical features provide the best clues for diagnosing MDCL and EDMD early in the disease, and we urge clinicians to become familiar with those phenotypes. WB for lamin A/C may contribute to diagnosis but requires technical expertise, and results are normal in many individuals with LMNA mutations. Because of the survival benefit of early diagnosis and treatment, we recommend that LMNA gene sequencing be performed in all patients with undiagnosed congenital muscular dystrophy and neck extensor weakness, all patients with genetically undiagnosed LGMD, and those with suggestive clinical signs and nonspecific histologic abnormalities.

The significance of neuroglobin in the brain

Since its discovery in 2000, neuroglobin (Nb) has been demonstrated to have an essential and conserved function in vertebrates with the consequential discovery of a neuroprotective role. Nb is a member of the globin superfamily and is predominantly expressed in neurons of the central and peripheral nervous system. Thorough studies have been performed to elucidate the molecular structure of Nb and its ligand binding characteristics. The precise physiological function and mechanism of action of Nb is beginning to be established, with a number of hypotheses having been put forward. While Nb shares an intrinsic affinity for low-molecular weight diatomic gases similar to other globins, the relatively low level of Nb expression in cerebral neurons places limitations on its potential to function as a reservoir for oxygen, especially during periods of acute ischemia. In vitro studies have suggested that the neuroprotective role of Nb may be due to its ability to scavenge reactive oxygen (ROS) and nitrogen (RNS) species. However other studies have proposed Nb as being part of a signalling chain that transmits the redox state of the cell that is protective against oxidative stress or that inhibits apoptosis. This review is intended to summarize the structural, genomic and functional data on neuroglobin to date, thereby providing perspectives for future research on these molecules that may have substantial biomedical implications.

Huntington CAG repeat size does not modify onset age in familial Parkinson's disease: the GenePD study

The ATP/ADP ratio reflects mitochondrial function and has been reported to be influenced by the size of the Huntington disease gene (HD) repeat. Impaired mitochondrial function has long been implicated in the pathogenesis of Parkinson's disease (PD), and therefore, we evaluated the relationship of the HD CAG repeat size to PD onset age in a large sample of familial PD cases. PD affected siblings (n = 495), with known onset ages from 248 families, were genotyped for the HD CAG repeat. Genotyping failed in 11 cases leaving 484 for analysis, including 35 LRRK2 carriers. All cases had HD CAG repeats (range, 15-34) below the clinical range for HD, although 5.2% of the sample (n = 25) had repeats in the intermediate range (the intermediate range lower limit = 27; upper limit = 35 repeats), suggesting that the prevalence of intermediate allele carriers in the general population is significant. No relation between the HD CAG repeat size and the age at onset for PD was found in this sample of familial PD.

Anti-melanin antibodies are increased in sera in Parkinson's disease

An increasing body of research suggests that a number of immune mechanisms play a role in degenerative pathways in Parkinson's disease (PD). In the current work we investigated a posited humoral immune response in this disorder. Sera from PD patients exhibited a significantly enhanced absorbance response on a novel ELISA for anti-melanin antibodies, compared to sera from age-matched control subjects. The enhanced ELISA absorbance response was specific for catecholamine-based melanins and was unrelated to antiparkinsonian dopaminergic medication. Further, the absorbance response was significantly and negatively correlated with disease duration. These data suggest that a specific humoral anti-melanin antibody response is present in PD and is more active in early disease. While the contribution of this novel immune response to the initiation and progression of this disorder is unclear, this finding supports the hypothesis that specific immune responses occurring in PD may respond to therapeutic interventions in this disorder.

The Gly2019Ser mutation in LRRK2 is not fully penetrant in familial Parkinson's disease: the GenePD study

BACKGROUND

We report age-dependent penetrance estimates for leucine-rich repeat kinase 2 (LRRK2)-related Parkinson's disease (PD) in a large sample of familial PD. The most frequently seen LRRK2 mutation, Gly2019Ser (G2019S), is associated with approximately 5 to 6% of familial PD cases and 1 to 2% of idiopathic cases, making it the most common known genetic cause of PD. Studies of the penetrance of LRRK2 mutations have produced a wide range of estimates, possibly due to differences in study design and recruitment, including in particular differences between samples of familial PD versus sporadic PD.

METHODS

A sample, including 903 affected and 58 unaffected members from 509 families ascertained for having two or more PD-affected members, 126 randomly ascertained PD patients and 197 controls, was screened for five different LRRK2 mutations. Penetrance was estimated in families of LRRK2 carriers with consideration of the inherent bias towards increased penetrance in a familial sample.

RESULTS

Thirty-one out of 509 families with multiple cases of PD (6.1%) were found to have 58 LRRK2 mutation carriers (6.4%). Twenty-nine of the 31 families had G2019S mutations while two had R1441C mutations. No mutations were identified among controls or unaffected relatives of PD cases. Nine PD-affected relatives of G2019S carriers did not carry the LRRK2 mutation themselves. At the maximum observed age range of 90 to 94 years, the unbiased estimated penetrance was 67% for G2019S families, compared with a baseline PD risk of 17% seen in the non-LRRK2-related PD families.

CONCLUSION

Lifetime penetrance of LRRK2 estimated in the unascertained relatives of multiplex PD families is greater than that reported in studies of sporadically ascertained LRRK2 cases, suggesting that inherited susceptibility factors may modify the penetrance of LRRK2 mutations. In addition, the presence of nine PD phenocopies in the LRRK2 families suggests that these susceptibility factors may also increase the risk of non-LRRK2-related PD. No differences in penetrance were found between men and women, suggesting that the factors that influence penetrance for LRRK2 carriers are independent of the factors which increase PD prevalence in men.

Sporadic inclusion body myositis: phenotypic variability and influence of HLA-DR3 in a cohort of 57 Australian cases

BACKGROUND AND AIMS

There have been few studies of the variability in the clinical phenotype in sporadic inclusion body myositis (sIBM) and it is not known whether the human leucocyte antigen (HLA) haplotype influences the phenotype and course of the disease. We studied a large cohort of patients with sIBM in order to determine the degree of phenotypic variability and different modes of presentation, as well as the influence of HLA haplotypes.

METHOD

A cross-sectional study of 57 biopsy-proven sIBM cases from three Australian centres was performed. Patients were interviewed and examined by a single investigator, and had HLA typing and autoantibody studies.

RESULTS

Although the initial symptoms in the majority of cases were attributable to quadriceps weakness (79%), a proportion of patients presented due to finger weakness (12%), foot drop (7%) or dysphagia (1.8%). Although the majority had the classic combination of quadriceps and forearm muscle involvement, some patients had predominantly forearm weakness with sparing of the quadriceps, or severe involvement of the anterior tibial muscles. Asymmetrical involvement was common (82%), particularly of the forearm muscles, with the non-dominant side being more severely affected in most cases. Carriage of the HLA-DRB1*0301 (DR3) allele was associated with lower quadriceps muscle strength and a more rapid decline in strength.

CONCLUSIONS

The findings emphasise the variability in the mode of presentation, patterns of muscle involvement and clinical course of sIBM in this population, and indicate that the HLA-DRB1*0301 (DR3) allele may influence the rate of progression as well as susceptibility to the disease.

Replication of association between ELAVL4 and Parkinson disease: the GenePD study

Genetic variants in embryonic lethal, abnormal vision, Drosophila-like 4 (ELAVL4) have been reported to be associated with onset age of Parkinson disease (PD) or risk for PD affection in Caucasian populations. In the current study we genotyped three single nucleotide polymorphisms in ELAVL4 in a Caucasian study sample consisting of 712 PD patients and 312 unrelated controls from the GenePD study. The minor allele of rs967582 was associated with increased risk of PD (odds ratio = 1.46, nominal P value = 0.011) in the GenePD population. The minor allele of rs967582 was also the risk allele for PD affection or earlier onset age in the previously studied populations. This replication of association with rs967582 in a third cohort further implicates ELAVL4 as a PD susceptibility gene.

Haplotypes and gene expression implicate the MAPT region for Parkinson disease: the GenePD Study

BACKGROUND

Microtubule-associated protein tau (MAPT) has been associated with several neurodegenerative disorders including forms of parkinsonism and Parkinson disease (PD). We evaluated the association of the MAPT region with PD in a large cohort of familial PD cases recruited by the GenePD Study. In addition, postmortem brain samples from patients with PD and neurologically normal controls were used to evaluate whether the expression of the 3-repeat and 4-repeat isoforms of MAPT, and neighboring genes Saitohin (STH) and KIAA1267, are altered in PD cerebellum.

METHODS

Twenty-one single-nucleotide polymorphisms (SNPs) in the region of MAPT on chromosome 17q21 were genotyped in the GenePD Study. Single SNPs and haplotypes, including the H1 haplotype, were evaluated for association to PD. Relative quantification of gene expression was performed using real-time RT-PCR.

RESULTS

After adjusting for multiple comparisons, SNP rs1800547 was significantly associated with PD affection. While the H1 haplotype was associated with a significantly increased risk for PD, a novel H1 subhaplotype was identified that predicted a greater increased risk for PD. The expression of 4-repeat MAPT, STH, and KIAA1267 was significantly increased in PD brains relative to controls. No difference in expression was observed for 3-repeat MAPT.

CONCLUSIONS

This study supports a role for MAPT in the pathogenesis of familial and idiopathic Parkinson disease (PD). Interestingly, the results of the gene expression studies suggest that other genes in the vicinity of MAPT, specifically STH and KIAA1267, may also have a role in PD and suggest complex effects for the genes in this region on PD risk.

Apolipoprotein epsilon alleles in sporadic inclusion body myositis: a reappraisal

Previous studies have differed as to whether APOE epsilon4 is a susceptibility factor for developing sporadic inclusion body myositis (sIBM), with a positive association being found only in an Australian cohort of cases. We have now re-examined this in a larger cohort of 57 sIBM cases and have also carried out a meta-analysis of all the published studies looking for evidence of a risk association or effect of APOE alleles on disease expression. Our findings argue against a specific role for any APOE alleles in conferring susceptibility to sIBM but have demonstrated a non-significant trend towards an earlier age-of-onset in patients with the epsilon2 allele.

Intracranial and dermatological cryptococcal infection in an immunocompetent man

We report the case of a 72-year-old man with a history of Parkinson's Disease who presented with a history of falls, cognitive impairment and depressed mood. Neurological examination revealed moderate rigidity and bradykinesia. Alterations to his anti-Parkinsonian medication resulted in improvements in his mobility but no change in mental state. He was also noted to have developed multiple raised skin lesions. One of these lesions was biopsied and grew Cryptococcus neoformans. He subsequently had a cerebral MRI scan which showed enhancing lesions, in the left parietal lobe and right superior cerebellar peduncle, consistent with intracranial cryptococcal infection. Images of one of the skin lesions and the cerebral MRI scan are shown.

Autosomal recessive hereditary spastic paraparesis with thin corpus callosum; report of two sisters

OBJECTIVES

To describe the clinical, cognitive, neurophysiological and radiological features of autosomal recessive hereditary spastic paraparesis (ARHSP) with thin corpus callosum.

PATIENTS AND METHODS

Two sisters with spastic paraparesis.

RESULTS

MRI brain scans demonstrated thinning of the corpus callosum. The clinical features were progressive spastic paraparesis beginning in the second decade, dysarthria, minor dystonia and chorea, distal weakness and cognitive impairment with frontal dysfunction. Motor compound action potentials are reduced and EMG demonstrated minor chronic denervation. Magnetic stimulation studies demonstrated increased threshold consistent with pyramidal system axonal loss.

CONCLUSIONS

AHRSP with thinned corpus callosum is a distinct clinical and genetic entity that may occur in non-Japanese individuals.

Case Scenarios to Assess Australian General Practitioners’ Understanding of Stroke Diagnosis, Management, and Prevention

Background and Purpose— Stroke represents the third-leading cause of death in Western society. Prompt and appropriate intervention for those with stroke or at risk of stroke is highly dependent on general practitioners’ (GPs’) knowledge and referral practices.

Methods— We randomly selected 490 eligible GPs from New South Wales, Australia, to complete our self-administered questionnaire. Case scenarios were used to assess GPs’ knowledge of transient ischemic attack/ stroke risk factors, stroke prevention strategies, and management of asymptomatic and symptomatic patients.

Results— We received 296 completed questionnaires (60% response rate). Nearly all GPs (286, 96.6%) strongly agreed or agreed that stroke is a medical emergency. Most were aware that management by multidisciplinary teams improves outcomes (strongly agree or agree, 279; 94.3%). GPs endorsed the effectiveness of aspirin and warfarin in reducing stroke morbidity. GPs also were aware of the benefit of carotid endarterectomy (CEA) for symptomatic patients with >80% carotid stenosis but were less aware of the value of CEA for symptomatic patients with moderate stenosis. Vascular surgeon was the specialist of choice for referral of patients with high-grade carotid stenosis. Few GPs reported having seen the Cochrane Collaboration reviews of CEA for symptomatic (3.0%) and asymptomatic (1.7%) patients.

Conclusions— GPs were well apprised of the evidence to support CEA for symptomatic patients with high-grade carotid stenosis. Our findings, however, invite more purposeful and effective education of GPs about stroke prevention, diagnosis, and management if optimal outcomes are to be realized.

Identifying the pattern of olfactory deficits in Parkinson disease using the brief smell identification test

BACKGROUND

Selective olfactory deficits occur in 70% to 90% of patients with Parkinson disease, independent of disease severity and duration. Olfactory testing may be a useful diagnostic aid for Parkinson disease, but the types of odors most commonly affected need to be identified.

OBJECTIVE

To determine the pattern and types of odors affected in Parkinson disease by means of the University of Pennsylvania 12-item Brief Smell Identification Test (B-SIT; Sensonics, Inc, Haddon Heights, NJ).

DESIGN

Testing patients with Parkinson disease and control subjects in 5 movement disorder clinics.

PARTICIPANTS

Forty-nine nondemented patients with Parkinson disease and 52 age- and sex-matched controls.

MAIN OUTCOME MEASURES

Normal or abnormal olfactory function was determined in each subject according to predetermined age and sex norms. Predictive statistics and discriminant function analyses were performed to determine the pattern and types of odors best discriminating patients from controls.

RESULTS

Abnormal olfactory function was present in 40 (82%) of patients compared with 12 (23%) of controls. The B-SIT score was unaffected by smoking behavior, disease duration, or severity. The sensitivity of the B-SIT for Parkinson disease was 0.82, with a specificity and predictive value of 0.82 and 0.77, respectively. Only 5 of the 12 B-SIT odors (gasoline, banana, pineapple, smoke, and cinnamon) were required to adequately discriminate patients with Parkinson disease from controls.

CONCLUSIONS

With the use of the B-SIT, 5 specific odors appear primarily affected in patients with Parkinson disease. Significantly, the ability of patients to detect some odors was unimpaired compared with that of controls. Better diagnostic aids could be developed on the basis of the selective pattern of hyposmia observed in Parkinson disease.