this effect. This effect is at least contemporaneous to and compounding to the processof demyelination that characterizes KD. Funded by NIH RNS065808A (ERB).

doi:10.1016/j.ymgme.2009.10.035

19. Carrier testing for MPS I and mucolipidosis II in the IrishTravellingCommunity

Karthryn Bootha,b, Karen Tyleea, Heather Churcha, Fiona Stuarta, Alan Coopera, aWillinkUnit, Genetic Medicine, St. Marys Hospital, Manchester M13 9WL, UK, bClinical Genetics,Belfast City Hospital, Lsiburn Road, Belfast BT 9 7AB, Ireland

The Irish Travelling Community is a distinct population on the island of Ireland.There is a tradition of first cousin marriage within the community. MPS I is presentat a high frequency in this population and Mucolipidosis II is also present withintwo large family within the community.

MPS I was exclusively caused by the common Western European, Caucasianmutation p.W402X. This invariably results in a severe (Hurler) phenotype. Mucolipi-dosis II was due to the common, pan ethnic mutation, c.3503_3504delTC. The WillinkLaboratory in collaboration with Northern Ireland Regional Genetics, has offered pre-natal diagnosis for both conditions to couples from this community. This is performedby assay of lysosomal a-L-iduronidase activity in chorionic villus or cultured amnio-cytes (for MPS I) and assay of multiple lysosomal hydrolases in cultured villus oramniocytes (for Mucolipidosis II). However, such an approach inevitably leads tounnecessary prenatal diagnoses being performed.

Once the underlying genetic lesions had been identified, carrier testing for bothconditions has been offered, either prior to conception or early in pregnancy. Bothmutations were identified by sequencing.

One hundred and ninety-seven relatives have been screened for p.W402X and 60for c.3503_3504delTC. 101 carriers of p.W402X and 25 carriers of c.3503_3504delTChave been identified. In this limited sample, two individuals were identified who car-ried both the p.W402X and c.3503_3504delTC mutations. This has allowed prenataldiagnosis to be offered only when a pregnancy is truly at risk for one of these twoconditions.

doi:10.1016/j.ymgme.2009.10.036

20. Cardiac valvular interstitial cells in MPS I

Elizabeth Braunlina, Jakub Tolara, Shannon Mackey-Bojackb, Tiwanda Marshc, PaulOrcharda, Frederick Schoend, aUniversity of Minnesota, Minneapolis, MN, USA, bThe JesseE. Edwards Registry, St. Paul, MN, USA, cNational Institute of Environmental HealthScience, Research Triangle Park, NC, USA, dHarvard Medical School, Boston, MA, USA

Background: Cardiac valve thickening by glycosaminoglycan-laden (GAG-laden)cells is clinically significant both in native mucopolysaccharidosis type I (MPS I)and despite hematopoietic stem cell transplantation or enzyme replacement therapy.

Hypothesis: We hypothesized that the GAG-laden cells in MPS I cardiac valves areactivated valvular interstitial cells (VICs), similar to those in valvular disease, adapta-tion to altered loading and living tissue valve replacements.

Methods: We performed pathologic analysis on cardiac atrioventricular valve tis-sue (two mitral, one tricuspid valve) from two infants with untreated MPS I and com-pared the results to mitral valve tissue (n = 2) from age-matched normal controls.

Results: We identified abundant small, spindle-shaped cells characteristic of rest-ing VICs within all layers of normal valve tissue. In MPS I, the deep cells within thesame layers of valve tissue were uniformly swollen with clear cytoplasm and eccen-tric nuclei. Immunohistochemical studies showed negative staining by these cells forCD68, CD3, and CD31 (indicating that they were not histiocytes, lymphocytes or vas-cular endothelial cells) and positive staining for vimentin, alpha-smooth muscle actin,and matrix-metalloproteinase-9, characteristics of activated VICs.

Conclusions: GAG-laden VICs within the cardiac valves of MPS I individuals have aphenotype similar to that of activated VICs, described in other models of extracellularmatrix remodeling and response to injury. This suggests that these cells may be con-tributing to valve dysfunction beyond accumulating GAG, and that such mechanismsmay be effective targets for inhibiting the deleterious effects of MPS I-related valvepathology.

doi:10.1016/j.ymgme.2009.10.037

21. Glycan-based biomarkers for the mucopolysaccharidoses

Jill Browna, J.R. Browna, R. Carrolla, N. Tambea, C. Glassa, K. Langfordb, S. Lec, A.Victoroffc, J.E. Wraithb, P. Dicksonc, B.W. Biggerb, B.E. Crawforda, aZacharon

Pharmaceuticals, San Diego, CA, USA, bUniversity of Manchester, Manchester, UK,cHarbor UCLA Medical Center, Torrance, CA, USA

The mucopolysaccharidoses (MPS) are caused by a deficiency in one of theenzymes responsible for the degradation of glycosaminoglycans (GAG). We havedeveloped biomarker detection methods based on the accumulation of glycan sub-strates. Many biomarkers have been considered including enzyme activity, proteinand mRNA markers, and measures of substrate accumulation. Quantification of sub-strate accumulation is potentially the most powerful approach given its direct rele-vance to pathology. However, historical methods to measure substrateaccumulation in lysosomal storage disease (LSD) have been hampered by the pres-ence of endogenous and extremely heterogeneous substrate material. To overcomethis challenge, the Sensi-Pro Substrate Assay was developed. By selectively amplifyingthe substrates accumulating due to the deficient enzyme, this method provides anassay with unique capabilities that can be applied across many (LSD). To validatethe method, we analyzed substrate in tissue and fluid samples from MPS subjects.Samples of serum, plasma, urine, and cerebrospinal fluid were obtained from MPSpatients, MPS animals, and normal subjects. The results demonstrate that the assaycan sensitively detect GAG accumulation with substantial variation in GAG levels insamples from MPS subjects compared to normal subjects. Response to enzymereplacement therapy was also demonstrated, and sample sizes of less than 50 l wererequired. At time of abstract submission, additional data collection to correlate theGAG levels to clinical endpoints are in process, creating the opportunity for a vali-dated biomarker of MPS disease severity and response to therapy in a variety of sam-ple types.

doi:10.1016/j.ymgme.2009.10.038

22. Small molecule inhibitors of glycosaminoglycan biosynthesisas substrateoptimization therapy for the mucopolysaccharidoses

Jill Brown, J.R. Brown, R. Carroll, C. Glass, B.E. Crawford, Zacharon Pharmaceuticals,San Diego, CA, USA

The mucopolysaccharidoses (MPS) are a family of lysosomal storage diseasescaused by a deficiency in enzymes responsible for the degradation of glycosaminogly-cans (GAG). Substrate optimization therapy (SOT) is a novel therapeutic approach forlysosomal storage disease based on selectively modifying the substrates to renderthem more readily degraded despite the presence of specific enzyme deficiencies,without reducing the overall amount produced or altering normal glycan function.In MPS, this is accomplished with small molecules targeting specific GAG biosyntheticenzymes, thus selectively and favorably modifying the glycan sulfation pattern. Toidentify drug candidates, we screened a library of 74,000 drug-like small moleculesfor modifiers of heparan sulfate biosynthesis using cell-based high throughput assaysand glycan structural analysis technology. Of the 264 hit compounds identified in theprimary screens, 30 were found to modify heparan sulfate biosynthesis in culturedcells. Four of these compounds reduce GAG accumulation in primary human fibro-blasts from MPS patients, and glycan structural analysis revealed changes consistentwith the intended SOT mechanism. At time of abstract submission, ongoing studiesare focused on analog design, synthesis, and testing to improve compound potency,and subsequent studies are planned to achieve the following preclinical product char-acteristics: (1) alteration of glycan biosynthesis to allow substrate degradationdespite presence of enzyme deficiencies in MPS, (2) efficacy in MPS animal models(potentially several MPS classes), (3) CNS penetrant, (4) pharmacokinetic profile sup-portive of convenient dosing, and (5) favorable safety profile.

doi:10.1016/j.ymgme.2009.10.039

23. Fabry disease identification

Marsha Browning, MGH/Harvard Medical School, Boston, MA, USA

Fabry disease is a treatable but clinically under recognized X-linked lysosomalstorage disease. High-risk populations, including patients with ischemic stroke andcardiovascular defects, if screened appropriately in a high-throughput, cost-effectivemanner, would demonstrate a higher prevalence of Fabry disease than previouslyreported in restricted patient populations. The prevalence of undiagnosed Fabry inend-stage renal disease, including dialysis and kidney transplant recipients, is 20–50 higher than that of the general population. An aggressive detection platform isneeded to identify previously undiagnosed or misdiagnosed patients, including arobust means to detect female Fabry patients, a previously underserved componentof these at-risk groups. The specific aims of this project are to: (1) To develop ahigh-throughput, cost-effective combined biochemical and molecular testing plat-form for Fabry Disease from blood and urine filter paper collection that can be adapt-

S12 Abstracts/Molecular Genetics and Metabolism 99 (2010) S8–S41