Lysosomal Enzymes in fibroblasts

Transcription

1 ERNDIM Administration Office Manchester Centre for Genomic Medicine th Floor, St Mary's Hospital, Oxford Road, Manchester M WL, United Kingdom. Tel: + Fax: + admin@erndim.org Lysosomal Enzymes in fibroblasts Scientific Advisor Dr Kees Schoonderwoerd Erasmus MC University Medical Center, P.O. Box CA Rotterdam Netherlands g.schoonderwoerd@erasmusmc.nl Scheme Organiser Dr. C.W. Weykamp Queen Beatrix Hospital MCA Laboratory P.O. Box NL GG Winterswijk Netherlands c.w.weykamp@skbwinterswijk.nl Annual Report Date of issue: August. Scheme Design The scheme has been designed, planned and coordinated by Dr Kees Schoonderwoerd as Scientific Advisor and Dr Cas Weykamp as Scheme Organiser (subcontractor on behalf of SKML); both appointed by and according to procedures laid down by the ERNDIM Board.. Samples All EQA materials are lyophilised samples of human fibroblasts. All samples were obtained following local ethical and consent guidelines. Table : Samples for the scheme Sample Disorder Enzyme defect LF MLD Arylsulphatase A LF Niemann Pick A/B Sphingomyelinase LF Hunter Iduronatesulphatase LF Niemann Pick A/B Sphingomyelinase LF GM (Morquio B) betagalactosidase LF Fabry alphagalactosidase. Shipment One shipment of samples was sent out to the laboratories, from countries, which registered for the scheme.. Receipt of results There were six submission deadlines from March to October at approximately week intervals. Laboratories were asked to submit results for each EQA sample by the relevant submission deadline using the results website Laboratories were asked to report the total protein and the activities for enzymes in absolute units and also as a percentage of their own laboratories control, see Table for details. Laboratories could submit results for as many, or as few, of these enzymes as they wished. Laboratories were also asked to select an interpretation of the results from a dropdown list on the results website. Page of

2 Annual Report (issued: August ) Table : Analytes to be measured Analyte Parameter Parameter Protein mg/vial Arylsulphatase A degr; degr; alphagalactosidase betagalactosidase alphaglucosidase betaglucosidase betahexosaminidase A alphaiduronidase Iduronate sulphatase Galactosylceramidase Sphingomyelinase. Scoring scheme For each enzyme criteria were scored: ) diagnosis and ) coefficient of variation (). A maximum of points was awarded for each criterion. For the protein value a maximum of points could be scored. Table : Scoring criteria Criteria Protein Enzymes <% %<<% >% correct partially correct incorrect <% %<<% >% The maximum possible score for the scheme was points ( enzymes plus the protein value). Laboratories that participated fully in the scheme (i.e. submitted enough results for their performance to be assessed) but scored less than % of their maximum possible score were considered to be unsatisfactory performers in the scheme. For example if a laboratory submitted results for analytes (protein & enzymes) their maximum possible score would be points so they would need to score or more points to be a satisfactory performer. If % of a laboratory s maximum possible score was not a full integer the number of points for satisfactory performance was rounded down to the next full integer... The participants had to select an interpretation from the dropdown list on the results website. correct indicated correct interpretation and correct measurement of enzyme activity level. In cases of control enzyme activity, the activity should be >% of the mean control while in case of a patient enzyme activity, the activity should be <% of the mean control. partially correct indicated incorrect interpretation and correct enzyme activity level or correct interpretation and incorrect enzyme activity level. incorrect indicated incorrect interpretation and incorrect enzyme activity level. Page of

3 Annual Report (issued: August ).. Coefficient of variation Results submitted for samples LF and LF were used to calculate the coefficient of variation () according to the following formula. = Activity LFactivity LF/mean With only two samples (LF and LF) it was not possible to calculate the standard deviation.. Results Sixtyeight laboratories (.% of registered laboratories) submitted sufficient results for their performance to be assessed and a further laboratories (.%) did not submit enough results for their performance to be assessed (partial submitters). One laboratory (.%) withdrew from the scheme and laboratories (.%) did not submit any results. Full details of each participating results are given in Appendix but a brief summary is presented here: Over % of all laboratories submitted results for or more enzymes, see Table. The proficiency per analyte is given in Table. Table shows the percentage of the maximum possible score for the laboratories that submitted results. laboratories that submitted results scored % or more of their maximum possible score and were classed as satisfactory performers. Table : Number of enzymes for which laboratories submitted results Number of Enzymes for which results were submitted Number of laboratories Total number of labs Page of

4 Annual Report (issued: August ) Table : Proficiency per analyte Analyte No of returns (% ) (% ) Total Proficiency (% ) Protein n.a. Arylsulfatase A αgalactosidase βgalactosidase αglucosidase βglucosidase βhexosaminidase A αiduronidase Iduronatesulphate sulphatase Galactocerebrosidase Sphingomyelinase = percentage of maximum possible score (for all laboratories that submitted results) Table : Percentage of maximum possible scores for laboratories that submitted results %age of maximum possible score % % % % % % % % % % % % % % % % % % % % % Totals No of submitting labs %age of submitting labs % %.% %.%.%.%.%.%.% % Sample LF can be regarded as an educational sample, derived from a MLD patient with a high residual arylsulphatase A activity. Samples LF and LF will also be regarded as educational samples. They were derived from a NiemannPick A/B patient with a mutation in the substrate binding site. Therefore they were missed by the participants that used the artificial substrate without sphingomyelin and many participants did not interpret this as a patient. Page of

5 Annual Report (issued: August ) Table : Number of enzymes for which submitting laboratories had satisfactory performance No of enzymes for which: No of enzymes for which: results were submitted by lab lab had satisfactory performance results were submitted by lab lab had satisfactory performance Page of

6 Annual Report (issued: August ). Comments here on overall scheme performance Overall all samples were correctly interpreted besides the educational samples.. Comparison to previous years In arylsulfatase and iduronatesulphate sulphatase activity measurements were not in the scheme, therefore no comparison can be made. For most enzymes there was no difference in the between and however there was a remarkable improvement in the number of participants with < for the analyte galactocerebrosidase. Table : Comparison between data from and %age of labs with: %age of labs with: No data < > No of labs No data < > No of labs Protein/vial Arylsulfatase A αgalactosidase βgalactosidase αglucosidase βglucosidase βhexosaminidase A αiduronidase Iduronatesulphate sulphatase Galactocerebrosidase % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % % Sphingomyelinase % % % % % % % (%) Analyte Kees Schoonderwoerd Scientific advisor Cas Weykamp Scheme Organiser Page of

7 Annual Report (issued: August ) Appendix (part ): Results per laboratory (see page for key) Protein/vial. Arylsulfatase A ;D ;DD+ D;R ;D R;D+ ;D;D R;D D;R ;D:D ;D+ :D ;DR :D αgalactosidase βgalactosidase. R R. ;D:D ;D+ R Page of

8 Annual Report (issued: August ) Mean (±SD) % Diagnoses incorrect Protein/vial.. ±.% Arylsulfatase A ;D;D+ R;. R αgalactosidase. βgalactosidase R. R;D.. :D.... :D :D ;D :D ±% ;D ;D ±% % ±% % % Key green cells = correct (<), correct interpretation and correct enzyme level red cells =Incorrect measurement, (>) or incorrect interpretation or enzyme level blue cells =not all samples measured D = enzyme activity patient sample > % control Fibroblast D+ = enzyme activity other samples < % control Fibroblasts D = patient sample not measured R = calculation not possible as one or both of LF and LF (duplicate samples) were not measured Page of

9 Annual Report (issued: August ) Appendix (part ): Results per laboratory (see page for key) αglucosidase βglucosidase ;D+ βhexosaminidase A αiduronidase :D+ ;D+. ;D+ ;D+ Page of

10 Annual Report (issued: August ) Mean (±SD) % Diagnoses incorrect αglucosidase D+... ±% % βglucosidase... ±%.% βhexosaminidase A αiduronidase ;D ±% ±% % % Page of

11 Annual Report (issued: August ) Appendix (part ): Results per laboratory (see page for key) Iduronatesulphate sulphatase Galactocerebrosidase Sphingomyelinase ;D ;D ;D ;D; :D+ R ;D;D;D ;D ;D ;D ;D;D ;D;;D;D;D Page of

12 Annual Report (issued: August ) Mean (±SD) % Diagnoses incorrect Iduronatesulphate sulphatase Galactocerebrosidase Sphingomyelinase ;D.. ;D;D;D. ;D;D ;D;D ±% ±% ;D ±% % % % Page of