Objective: There is currently no recognised method for themeasure-ment of LAL in DBS. Our aim was to develop a method using DBS andvalidate the technique using samples from patients with CESD.

Methods: LAL was extracted from DBS with distilled water andincubated with 4 mU-palmitate in acetate buffer pH 4.0 andcardiolipin as an activator of LAL. Lalistat 2 was used as a specificinhibitor of LAL and activity estimated by measuring total lipaseactivity and lipase activity in the presence of Lalistat 2. LAL activitywas determined by subtracting activity measured in the inhibitedreaction from that in the uninhibited reaction. The assay wasperformed using 96 well plates and read at 355 nm/460 nm.

Results: LAL activity in normal controls was 1.70 – 3.40 umol/l/hr.Samples from patients with confirmed CESD had significantlyreduced LAL activity - <0.05 umol/l/hr. Activity in carriers was inthe range 0.73-1.02 umol/l/hr.

Conclusions: Measurement of LAL using DBS is made difficult bythe presence of other forms of lipase in whole blood. Lalistat 2 is aspecific inhibitor of LAL which allows the reliable determination ofLAL in DBS. Results show the method differentiates clearly betweennormal controls, carriers and affected cases.

doi:10.1016/j.ymgme.2011.11.068

Multiparametric 3.0 Tesla MRI of the Brain in Fabry Disease

Eric Hanson a, e, Jonathan Bernstein b, Cayce Roach c, Priya Simonelli d,Daniel Morris d, Kathyrn Lowery d, William Orrison a, f, g, aTier 7Research and Development, Las Vegas, NV, USA, bChildren's Center forCancer, Las Vegas, USA, cTemple University School of Medicine,Philadelphia, USA, dTouro University Nevada, Las Vegas, USA, eUniversityof Nevada Las Vegas, Las Vegas, USA,

fAdvanced Medical Imaging and

Genetics, Inc. (Amigenics), Las Vegas, USA, gCHW Nevada ImagingCompany, Las Vegas, USA

Purpose: This study was performed to identify incrementaldiagnostic information that can be captured with multi-parametricMRI studies of the brain in patients with Fabry disease (FD). Asecondary goal was the clinical utilization of a checklist of MRI brainfindings in FD developed based on a literature review to assist readersin capturing the complex findings of this disease.

Materials and Methods: Five cases (n=3 male) with FD (agerange19-48 years) were evaluated on a 3.0 T MRI system with thefollowing protocols: structural MRI, diffusion tensor imaging (DTI) ofthe corpus callosum, multi-voxel brain MR spectroscopy (MRS), andnoncontrast-enhanced MR angiography (NCE-MRA).

Results: Novel findings of hippocampal atrophy (n=2), fornixatrophy (n=2), and abnormal quantitative corpus callosum DTIfindings (n=5) were identified. At least one white matter lesion waspresent in all patients. Basilar artery dolichoectasia (n=1) andmiddle cerebral and basilar artery ectasia (n=1) were identified inseparate patients. NCE-MRA identified bilateral fetal origin posteriorcerebral arteries in one male patient. Periventricular leukoencephalo-pathy in the parietal lobe was identified in one female patient.Abnormal choline MRS values were identified in all patients.

Conclusions: Improved clinical assessment of patients with FD canbe accomplished using a multiparametric imaging including structur-al 3 T MRI, DTI, NCE-MRA, and MRS. In addition, utilization of a FDBrain MRI checklist assisted researchers in the assessment of theheterogeneous and numerous abnormalities, and reading fo theimages obtained in this pilot study. The novel findings of hippocam-pal atrophy, fornix atrophy, and abnormal corpus callosum DTIfindings warrant further study.

doi:10.1016/j.ymgme.2011.11.069

Mucopolysaccharidosis VI (Maroteaux-Lamy Syndrome):Development of Clinical and Laboratory Guidelines for Diagnosis

Paul Harmatz 1, Children's Hospital & Research Center Oakland,Oakland, California, USA

Mucopolysaccharidosis (MPS) VI is a lysosomal storage disease inwhich deficient N- acetylgalactosamine 4-sulfatase (arylsulfatase B, orASB) impairs degradation of dermatan sulfate. Accurate diagnosis iscritical to ensure that patients receive appropriate enzyme replacementtherapy. Reviewof laboratory tests formucopolysaccharidoses and theiruse in diagnosis ofMPSVIwas the topic of a recentexpert panelmeeting,inclusive of clinicians and laboratory directors.

Clinicians completed a survey on MPS VI diagnosis practices. Therewas consensus on the requirement to evaluate ASB enzyme activity toobtain a final diagnosis. While the reported use of additional tests wasvariable, such as urinary glycosaminoglycans (uGAG) analysis (qualita-tive and quantitative), molecular testing, and multiple lysosomalenzymes testing, it was recommended that these laboratory tests beincluded as part of diagnosis of MPS VI. All participants emphasized theimportance of direct communication between the diagnostic laboratoryand clinician.

In addition to high clinical suspicion, diagnosis of MPS VI requiresquality results from tests run at laboratories with expertise in MPStesting and result interpretation. The use of multiple specimens andtests, such as qualitative and quantitative uGAG, multiple lysosomalenzyme activities, and molecular testing, when possible, was theunanimous recommendation of the panel.

*MPS VI Laboratory Diagnostic Scientific Summit participants:Bodamer O, Burin MG, D'Almeida V, Eng CM, Fietz M, Giugliani R,Harmatz P, Hendriksz CJ, Hwu WL, Ketteridge D, Lukacs Z,Mendelsohn NJ, Miller N, Pasquali M, Schenone A, SchoonderwoerdK, Winchester B, Wood T.

1On behalf of the participants at the MPS VI Laboratory Diagnostics Scientific Summit.

doi:10.1016/j.ymgme.2011.11.070

Large Animal Models of Lysosomal Storage Diseases: Lessons onthe Limits of Gene/Enzyme Therapy

Mark Haskins a, Meg Sleeper a, Gus Aguirre a, Steven U. Walkley b, VanKnox a, Charles Vite a, Richard Steet c, Brittney Gurda a, Jim Wilson a,Alberto Auricchio d, Lachlan Smith a, Lilla Simonaro e, KatherinePonder f, aUniversity of Pennsylvania, Philadelphia, Pennsylvania, USA,bAlbert Einstein College of Medicine, Bronx, New York, USA, cUniversity ofGeorgia, Athens, Georgia, USA, dTelethon Institute Of Genetics AndMedicine, Naples, Italy, eMount Sinai Medical Center, New York, NY, USA,fWashington University in St. Louis, St. Louis, Missouri, USA

Dog and cat orthologs of human genetic disease provide theopportunity to investigate the pathogenesis of these disorders and testtherapeutic efficacy and toxicity in large species with naturallyoccurring disease. The long-lived large species, for which there areboard-certified clinical specialists and sophisticated techniques toevaluate disease including echocardiography and magnetic resonanceimaging, provide an important intermediate step in translationalmedicine from the mouse to mankind. A group of investigators havecollaborated to treat dogs and cats with various lysosomal storagediseases including mucopolysaccharidosis (MPS) I, VI, and VII, alpha-mannosidosis, and Niemann Pick disease type C. Many were treatedusing retroviral and adeno-associated viral vectors from 3 days to60 days of age. Serum enzyme activities have ranged from 10% ofnormal to 60-fold normal, has been maintained for up to 11 years insome animals, and has produced some significant improvements in

Abstracts / Molecular Genetics and Metabolism 105 (2012) S15–S69 S33