Heterogeneous Spectrum of CFTR Gene Mutations in Korean Patients with Cystic Fibrosis / 대한진단검사의학회지

BACKGROUND: Cystic fibrosis (CF) is one of the most common hereditary disorders among Caucasians. The most common mutations of the cystic fibrosis transmembrane conductance regulator (CFTR) gene have been well established among Caucasian populations. In Koreans, however, there are very few cases of genetically confirmed CF thus far, and the spectrum of mutations seems quite different from that observed in Caucasians. METHODS: In the present study, we describe the cases of 2 Korean CF patients, present sequencing results identifying mutations in their CFTR gene, and summarize the results of CFTR mutational spectrum from previously reported Korean CF patients. The mutations described were identified by performing direct sequencing analysis of the complete coding regions and flanking intronic sequences of the CFTR gene, followed by multiplex ligation-dependent probe amplification (MLPA) analysis in order to detect gene deletions or duplications that could not be identified by a direct sequencing method. RESULTS: Three CFTR mutations were identified in the 2 patients, including p.Q98R, c.2052delA, and c.579+5G>A. In an analysis of 9 Korean CF patients that included the 2 patients presented in this study, p.Q98R mutation was the only recurrently observed mutation with a frequency of 18.8% (3/16 alleles). Furthermore, only one of the mutations (c.3272-26A>G) was found among the 32 common mutations in the screening panel for Caucasians from the Cystic Fibrosis Mutation Database. CONCLUSIONS: Sequencing of the entire CFTR gene followed by MLPA analysis, rather than using the targeted sequencing-based screening panel for mutations commonly found in Caucasian populations, is recommended for genetic analysis of Korean CF patients.

Evaluation of MicroScan Synergies plus Positive Combo 3 Panels for Identification and Antimicrobial Susceptibility Testing of Staphylococcus aureus and Enterococcus Species / 대한진단검사의학회지

BACKGROUND: Few studies have evaluated the performance of the recently introduced MicroScan Synergies plus Positive Combo 3 Panels (SIPC3) (Dade Behring Inc., USA). We evaluated the clinical efficacy of the panels in identification (ID) and antimicrobial susceptibility testing (AST) of Staphylococcusaureus and enterococci. METHODS: To evaluate the panels' accuracy of identification, the results obtained using the test panels were compared with those obtained by using conventional biochemical tests in conjunction with VITEK 2 system (bio-Merieux, USA). In addition, the AST results obtained using the panels were compared with those obtained by performing CLSI broth microdilution. RESULTS: The overall agreement between the approaches for the ID of S. aureus and enterococci was 100% and 96%, respectively. The categorical and essential agreements (CA and EA) for S. aureus were 98%, each. Very major errors (VME), major errors (ME), and minor error (mE) for S. aureus were 0.45%, 0.3%, and 4.2%, respectively. The majority of VMEs were for oxacillin (8.6%), penicillin (2.0%), erythromycin (7.9%), clindamycin (3.8%), and tetracycline (4.1%). For enterococci, the CA, EA, VME, ME, and mE were 88.8%, 93.7%, 4.4%, 0%, and 2.8%, respectively. The 80.5% (29/36) of Enterococcus faecium had concordant ID with the reference. Most of the categorical errors (3 VMEs and 14 mEs) were observed for quinupristin/dalfopristin (Synercid; Catalytica Pharmaceuticals Inc., USA). CONCLUSIONS: The panels compared favorably with conventional methods for the ID and AST of S. aureus. However, we expected a better performance for ID of E. faecium and AST using Synercid.

Immature Platelet Fraction: Establishment of a Reference Interval and Diagnostic Measure for Thrombocytopenia / 대한진단검사의학회지

BACKGROUND: Immature platelet fraction (IPF, %) is a measure of reticulated platelets (RPs), which represents the state of thrombopoiesis. The IPF is obtained from an automated hematology analyzer as one of the platelet parameters. This study was performed to establish reference intervals of IPF and its cut-off values for the differential diagnosis of thrombocytopenia. METHODS: Blood samples from 2,039 healthy individuals (1,161 males, 878 females) were obtained to establish reference intervals. The patient group included patients with idiopathic thrombocytopenic purpura (ITP) (N=150) and aplastic anemia (AA) (N=51) with platelet counts of less than 100x10(9)/L. We evaluated the reliability of the IPF measurements, the reference intervals, and cut-off value for the diagnosis of ITP. RESULTS: The reference intervals of IPF were 0.5-3.2% in males and 0.4-3.0% in females (95% confidence interval). The median IPF% of ITP and AA were 7.7% (range, 1.0-33.8%) and 3.5% (range, 0.6-12.9%), respectively. Statistical analysis revealed a significant difference between the IPF% of ITP and AA (P<0.0001). The cut-off value of IPF for differentiating ITP from AA was 7.3% with a sensitivity and specificity of 54.0% and 92.2%, respectively. CONCLUSIONS: A rapid and inexpensive automated measurement of IPF can be integrated as a standard parameter to evaluate the thrombopoietic state of the bone marrow. This study determined the reference intervals of IPF from a large population of healthy individuals, including children. Further studies are needed to establish the clinical utility of IPF.

Blood Chimerism in a Dizygotic Dichorionic Pregnancy / 대한진단검사의학회지

Blood chimerism in twins is known to occur through the transfer of hematopoietic stem cells between the fetuses via a common placenta. We present a case of blood chimerism in a dizygotic dichorionic twin pregnancy. The female twin was delivered at 34 weeks of gestation, and the male twin was stillborn. Pathologic examination confirmed dichorionic diamniotic placentas. The karyotype of the female child was obtained using peripheral blood sample, and it revealed a mixture of 46,XX and 46,XY cells (chi 46,XY[13]/46,XX[7]). FISH analysis performed on the buccal cells by using CEP X/Y probe (Abbott Molecular Inc., USA) revealed 100% XX signals (nuc ish Xcen(DXZ1x2)[500]). Gross examination of the external genitalia and abdominal ultrasonography revealed no definitive abnormal findings in relation to sex differentiation. When XX/XY chimerism is present in blood lymphocytes, careful examination of external genitalia and reproductive organs and further studies are required to detect chimerism in non-hematopoetic tissues. This is a rare case of blood chimerism in dichorionic placentas, in contrast to those in monochorionic placentas.