[Approach for prevention of medical test malpractice using ISO 15189].

With the increasing need for medical laboratory data, the importance of the medical laboratory in medical care has grown exponentially. Therefore, it is necessary that the medical laboratory provide the doctor and the patient receiving medical care with accurate, precise, and reliable medical laboratory data. Quality assurance and safety management in the medical laboratory are necessary to prevent medical test malpractice, which would lead to a medical accident, and to manage the overall processes required to provide high quality medical laboratory data. ISO 15189 is an international standard known as an organizational management tool for medical laboratories. Our medical laboratory acquired this ISO in March 2005 and we utilized PDCA cycle as required by the international standard in order to establish appropriate safety management and crisis control. We introduced practices for quality improvement and prevention of medical test malpractice proposed by the ISO committee of our medical laboratory and describe these practices in this report.

Single nucleotide polymorphisms and haplotypes of protein C and protein S genes in the Thai population.

Protein C (PC) and protein S (PS) play key roles in an anticoagulant pathway in order to control the haemostatic system. We identified single nucleotide polymorphisms (SNPs) and/or haplotypes in the promotor and exons of the whole PC and PS genes and in the 3'-untranslated region of the PS gene in 55 Thai individuals. The PC gene revealed 10 haplotypes. One synonymous SNP at 2196 was found in the normal Thai population with a minor allele frequency of 4.90%. One homozygous mutation in exon 7, R147W, co-segregated with the synonymous SNP 2196 (homozygote) of the PC gene, resulting in decreased PC activity and antigenic levels. The PS gene revealed three haplotypes with two frequent dimorphisms in exon 15 and the 3'-untranslated region. The most frequent haplotype in the PS gene was H3 (wild type). There was no correlation between the haplotypes of PC and PS genes with functional and antigenic levels of PC and PS.

Protein S and protein C gene mutations in Japanese deep vein thrombosis patients.

OBJECTIVES: Coagulation factor V Leiden has not been detected in Japanese patients suffering from thrombosis. Hitherto, the constitutional background of Japanese thrombotic patients has never been systematically examined. We have performed a systematic investigation to determine pathogenesis for deep vein thrombosis in a Japanese population. DESIGN AND METHODS: Routine coagulation and fibrinolysis tests were performed to determine the activities of protein S, protein C, antithrombin, plasminogen and fibrinogen. Gene analysis was performed in thrombotic patients having low activities of these factors. RESULTS: Our study indicates that the frequency (19/85 = 0.22) of mutations of protein S gene in the Japanese patients was 5-10 times higher than that of mutations of protein S gene in Caucasian patients, and the frequency (8/85 = 0.09) of mutations of protein C gene was almost three times higher than that of Caucasian patients. The frequency of antithrombin gene mutation was similar in both populations. CONCLUSION: Our study reinforces that the genetic anomaly in the protein S/protein C anticoagulation system is an important risk factor for thrombophilia in the Japanese population.

Characterization of two novel mutations of the antithrombin gene observed in Japanese thrombophilic patients.

We investigated the molecular basis of reduced functional levels of antithrombin (AT) in two individuals suffering from thromboembolic events. In each case direct sequencing of amplified DNA revealed 13,260-13,262 del in one patient and 2511C>A in the other patient, predicting a heterozygous E381del and P16H, respectively. Both patients had no 20210A allele and factor V Leiden mutation. To understand the molecular mechanism responsible for antithrombin deficiency, stable expression experiments were performed using HEK293 cells transfected with the expression vector containing the wild-type or the mutated recombinant cDNA. In these experiments, the media levels of the two mutated antithrombins were the same as that of wild type, but the specific activity of the E381del mutant decreased significantly compared with that of wild type. These results showed that the E381del mutation was responsible for type II deficiency, whereas the other mutation, P16H, did not produce any definite abnormality which could contribute to antithrombin deficiency.

Combined protein C and protein S deficiency in a family with repetitive thromboembolism and segregated gene mutations.

A young man with repetitive deep venous thrombosis of the legs and the inferior vena cava, and his family were eventually diagnosed by means of molecular genetic analysis as having both hereditary protein C and protein S deficiency. There have been a few reports of families with combined protein C and protein S deficiency and only one report of such a family characterized at the DNA level. This was the first reported family in Japan with combined deficiency of protein C and protein S accompanied by segregation of gene lesions.

Analytical goals for coagulation tests based on biological variation.

Allowable imprecision and bias reference limits for laboratory data can be calculated based on measurements of biological variation. Although biological variation of clinical chemical data has been reported from many laboratories, there have been few reports of biological variation in coagulation tests. In this study, we calculated the biological variation of 13 coagulation tests in the clinical laboratory of Kyushu University Hospital and determined allowable imprecision and bias limits of variation. The participating subjects were 17 healthy individuals: three males and two females in their 20s, two males and two females in their 30s, one male and four females in their 40s, and two males and one female in their 50s. Monthly measurements were performed before breakfast 12 times from June 2001 to May 2002 and allowable imprecision and bias limits were calculated. Taken together with coefficient of variation of control plasma used in daily laboratory work at the hospital, the allowable imprecision limits of intra-laboratory variation determined in this study appear to be in attainable ranges.

Identification of simultaneous mutation of fibrinogen alpha chain and protein C genes in a Japanese kindred.

Afibrinogenaemia usually induces a bleeding tendency during infancy, whereas protein C deficiency increases susceptibility to thrombosis in children or adolescence. Mutations of these genes have been, therefore, established as independent risk factors for coagulation disorders. We describe the homozygous mutation of the fibrinogen alpha chain gene and additional heterozygous mutation of the protein C gene in a male infant who showed prolonged umbilical bleeding after birth. On examination, the plasma fibrinogen was undetectable, and the activity and antigen level of protein C were reduced. The patient showed no fibrinogen Aalpha chain as well as Bbeta and gamma chains by Western blotting. The sequencing analysis showed the homozygous deletion of 1238 bases from intron 3 at position 2008 to intron 4 at position 3245 in the fibrinogen alpha chain gene. Both parents were heterozygous carriers of this mutation. In this patient, an additional mutation was also detected in the protein C gene: the heterozygous deletion of exon 7 at position 6161-6163 or 6164-6166, resulting the deletion of one amino acid (Lys150 or 151). His mother was also a carrier of this mutation. As the simultaneous mutation of the fibrinogen alpha chain and protein C genes has not been previously reported, the influence of the interaction between these two mutations on the clinical manifestations of this patient should be carefully monitored for a long period.