was higher in LOMS than in AOMS (17.6% vs. 5.3%, p < 0.05). 17 pa-tients (23.3%, 17/73) in LOMS group were initially misdiagnosed asdisorders other than MS.

Conclusion: LOMS happened with a relative high frequency inPDDD. LOMS in PDDD had similar clinical and radiological featuresas other reports. HLA-DRB1*0801 may be related to the late onsetof MS in PDDD. Vigilance is necessary to MS in older patients be-cause of its unusual presentation in this population.

doi:10.1016/j.jocn.2009.07.057

33. Longitudinally Extensive Myelopathy in Caucasians: a WestAustralian Study of 26 cases from the Perth DemyelinatingDiseases Database

Wei Qiu 1, Jing-Shan Wu 1, Mei-Ni Zhang 2, Takuya Matsushita 3,Jun-ichi Kira 3, William M Carroll 1, Frank L Mastaglia 1, Allan GKermode 1

1 Centre for Neuromuscular and Neurological disorders, University ofWestern Australia, and Department of Neurology, Sir Charles Gaird-ner Hospital, Queen Elizabeth II Medical Centre, Perth, WesternAustralia2 First Hospital of Shanxi Medical University, Taiyuan, China3 Department of Neurology, Neurological Institute, Graduate School ofMedical Sciences, Kyushu University, Fukuoka, Japan

Objectives: To characterize the clinical, radiological and labora-tory features of longitudinally extensive myelopathy (LEM) in thePerth Demyelinating Diseases Database (PDDD).

Methods: A total of 26 patients with LEM were identified withina large cohort of 983 patients in the PDDD. The clinical parameters,cerebral and spinal MRI data and aquaporin-4 IgG (AQP4-IgG) resultswere retrospectively studied.

Results: 26 patients with LEM were classified as conventionalMS (CMS) in 13, neuromyelitis optica (NMO) in 7, and isolatedLEM (1 monophasic and 5 recurrent) in 6. Lesions in CMS weremostly located in the lower cervical cord (C4-C7), which was signif-icantly different from the NMO and RLEM cases (p < 0.05) in whichthoracic lesions were more common. On axial MRIs LEM lesionsoccupied the centre of the cord or the whole cord in all 6 of the iso-lated LEM cases, 5/7 (71%) of the NMO cases and 9/13 (69%) of theCMS cases. The average onset age in the whole group was 37.1years (range18-63 years) and was significantly lower in the CMSgroup (30.6; P < 0.05). The severity of disability was highly variablebut was greater in the NMO than the CMS group: the mean EDSS atlast visit was 8.0 in the NMO group and 5.1 in the CMS group(p < 0.05). LEM occurred as the initial presentation in 13 of the26 patients. Only one patient (5%, 1/20) was seropositive forAQP4-IgG.

Conclusion: LEM did occur in CMS, as well as NMO and isolatedLEM. Patients with LEM in our group had highly heterogeneous clin-ical characteristics. AQP4-IgG seropositivity was very low in our co-hort despite the presence of LEM.

doi:10.1016/j.jocn.2009.07.058

34. Frequency of HLA-DRB1 alleles and disease-modifying effectsin a large West Australian multiple sclerosis cohort

Jing-Shan Wu 1, Wei QIU 1, Alison Castley 2, Joyce Joseph 1, William MCarroll 1, Frank Christiansen 2, Frank L Mastaglia 1, Allan G Kermode 1

1 Centre for Neuromuscular and Neurological disorders, University ofWestern Australia. Australian Neuromuscular Research Institute, SirCharles Gairdner Hospital, Western Australia2 Department of Clinical Immunology & Immunogenetics, Royal PerthHospital, PathWest, Western Australia. School of Pathology and Labo-ratory Medicine, University of Western Australia

Introduction: Genetic susceptibility to multiple sclerosis (MS) ispredominantly determined by polymorphism at the HLA-DRB1 genelocus. The HLA-DRB1 *1501 allele is found in over half of MS cases inCaucasians. Western Australia (WA) is a geographically isolatedState with a reasonably uniform and stable Caucasian population,providing a unique opportunity for genotype-phenotype studies.

Methods: The Perth demyelinating disease database (PDDD) re-cruited over 1000 patients representing approximately two-thirdsof the MS population in WA. HLA-DRB1 genotyping was performedusing a high-resolution DNA sequencing technique on a cohort of�500 well-characterized MS patients from the PDDD and geno-type-phenotype correlations were examined. Among the study par-ticipants, 465 had clinically definite or probable MS (MS),comprising 41 cases of primary progressive MS (PPMS) and 425cases of relapsing remitting/ secondary progressive MS (RR/SPMS).A cohort of 189 Caucasian individuals from a rural WA Communitycomprised the control group.

Results: A total of 34 DRB1 allele variants were detected in thestudy cohort. A significantly increased frequency of DRB1*1501was observed in the RR/SPMS (54.1%, p < 10�6 OR = 4.8) and PPMS(58.5%, p < 10�6) groups compared with the control group (19.5%).Frequencies of four other DRB1 alleles (DRB1*0101, *0701, *0901and *1101) were significantly decreased in the MS group. No associ-ation was found between the presence of DRB1*1501 and gender,age of onset, disease duration or frequency, of brain or spinal MRIor visual evoked potential abnormalities. DRB1*1501 carriers hadhigher positive rate of oligoclonal bands (67%) compared withnon-DRB1*1501 carriers (49.4%, p = 0.027). Frequency ofDRB1*1501 homozygosity was not increased in the MS cohort.However, a gene-dose effect was found for level of disability (medianEDSS: DRB1*1501 homozygote 4.0, heterozygote 3.0, and DRB1*1501negative group 2.5, p = 0.009). A correlation was also observedbetween DRB1*0301 gene-dose and spinal cord MRI abnormalities(100% in homozygotes, 94.1% in heterozygotes and 85.6% inDRB1*0301 negative cases, p = 0.026).

Conclusion: This is the largest Caucasian MS cohort studied todate in the Southern Hemisphere. Our results demonstrate theimportant role of HLA-DRB1 alleles in determining risk of MS andclinical outcomes in this population.

doi:10.1016/j.jocn.2009.07.059

35. Preliminary findings: a retrospective study of ischaemicstroke in children with congenital and acquired cardiac disease

Michael Cardamone 1, Darren Hutchinson 2, Michael Cheung 2, LeeColeman 3, Mark T Mackay 1

1 Department of Neurology, Royal Children’s Hospital, Parkville,Australia2 Department Cardiac Services, Royal Children’s Hospital, Parkville,Australia3 Department Medical Imaging, Royal Children’s Hospital, Parkville,Australia

Background: Cardiac disease is considered the most importantpreviously identifiable risk factor for ischaemic stroke in the

1536 Abstracts / Journal of Clinical Neuroscience 16 (2009) 1514–1546