title: Comparison of serum creatine kinase estimation with short tandem repeats based linkage analysis in carriers and affected children of Duchenne muscular dystrophy.
abstract: BACKGROUND
  Duchenne Muscular Dystrophy (DMD) is an X-linked recessive lethal, genetic disorder characterised by progressive weakness of skeletal muscles which is untreatable and transmitted to males by carrier females. Advances in laboratory techniques now focus direct mutational analysis as the most reliable and indirect analysis based on Short Tandem Repeats (STR) based linkage analysis as feasible, inexpensive, and efficient method for carrier detection and prenatal diagnosis. The objective of this study was to compare the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and diagnostic efficiency of Serum Creatine Kinase (SCK) with Short Tandem Repeats (STR) based linkage analysis in carriers and affected children of Duchenne Muscular Dystrophy.
  
  
  METHODS
  The study was carried out from Dec 2006 to Dec 2007 in families having index clinical cases of DMD who were referred from different hospitals for evaluation/workup of DMD. SCK was done as a preliminary investigation in all index cases. The PCR assay with STR based linkage analysis with Intron 44, 45, 49 and 50 of DMD gene were performed in all families. Six families were informative with Intron 44 of DMD gene and one family was non-informative with all four intronic markers of DMD. SCK analyses were done in all the family members and compared with PCR analysis in informative families. SCK was not performed on Chorionic villous sample (CVS) done for prenatal diagnosis of DMD, and CVS and non-informative family members were excluded from the study.
  
  
  RESULTS
  In carriers of DMD, the sensitivity and negative predictive value of SCK were 33.3%, and specificity and positive predictive were 100% with diagnostic efficiency of 50%. In affected cases of DMD the sensitivity and negative predictive value of SCK were 100%, and specificity and positive predictive were 91% and 88.8% respectively and diagnostic efficiency of 94.1%.
  
  
  CONCLUSIONS
  The SCK is an excellent screening test for affected cases of DMD. For carrier identification we have to resort on PCR analysis so as to provide safer diagnostic tool for genetic counselling and prenatal diagnosis.
authors: Armed Forces Institute of Pathology, Rawalpindi, Pakistan. riznajmi20011@hotmail.com
authors: Rizwan
authors: R
authors: Hashim
authors: Sajida
authors: S
authors: Shaheen
authors: Suhaib
authors: S
authors: Ahmad
authors: Abdus
authors: A
authors: Sattar
authors: Farooq Ahmad
authors: FA
authors: Khan
mesh_terms: D000328:Adult; D000368:Aged; D003402:Creatine Kinase / Q000097:blood*; D003430:Cross-Sectional Studies; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D008040:Genetic Linkage; D006579:Heterozygote; D006801:Humans; D007438:Introns / Q000235:genetics; D008297:Male; D018895:Microsatellite Repeats; D008875:Middle Aged; D020388:Muscular Dystrophy, Duchenne / Q000235:genetics*; D012680:Sensitivity and Specificity; D055815:Young Adult
chemical_list: D003402:Creatine Kinase