Correlation of major cytogenetic response with a pharmacogenetic marker in chronic myeloid leukemia patients treated with imatinib (STI571).

PURPOSE: Imatinib, an inhibitor of the Bcr-Abl tyrosine kinase, is indicated for the treatment of patients with Philadelphia chromosome-positive chronic myeloid leukemia. We examined genotypes from patients enrolled in the International Randomized Study of IFN-alpha versus STI571 in an attempt to identify factors that associate with cytogenetic response. EXPERIMENTAL DESIGN: Sixty-eight polymorphic loci in 26 genes were examined in a subset of 187 patients (imatinib-treated patients, n = 113; IFN + 1-beta-D-arabinofuranosylcytosine-treated patients, n = 74). Correlations between genotype and major cytogenetic response (MCyR) were examined by Fisher's exact tests. Multivariate and survival analyses were also performed. RESULTS: A significant association between MCyR and the rs2290573 polymorphism mapped to 15q22.33 was observed in imatinib-treated patients (P = 0.00037, Bonferroni corrected P = 0.025). Individuals with a CC genotype at this locus had a MCyR rate of 52% compared with individuals with a CT or TT genotype that had a MCyR rate of 89% (odds ratio, 6.72; 95% confidence interval, 1.51-29.91). In a multivariate analysis, the rs2290573 polymorphism was significant, whereas Sokal score was not. Time to progression analysis illustrated a significant difference based on genotype for the rs2290573 polymorphism. CONCLUSIONS: A significant association was identified between the genetic polymorphism rs2290573 and MCyR in imatinib-treated patients. This polymorphism is located in the intronic sequence of a putative gene with a tyrosine kinase domain. Multivariate analysis suggests that an individual's genotype for rs2290573 has more predictive value for MCyR than prognostic variables such as Sokal score. The clinical relevance of these results requires validation in future clinical trials.     

Cytogenetic and molecular characterization of random chromosomal rearrangements activating the drug resistance gene,MDR1/P-glycoprotein,in drug-selected cell lines and patients with drug refractory ALL

Drug resistance, both primary and acquired, is a major obstacle to advances in cancer chemotherapy. In vitro, multidrug resistance can be mediated by P-glycoprotein (PGY1), a cell surface phosphoglycoprotein that acts to efflux natural products from cells. PGY1 is encoded by the MDR1 gene located at 7q21.1. Overexpression of MDR1 has been demonstrated in many cancers, both in patient tumors and in cell lines selected with a variety of chemotherapeutic agents. Recent studies in drug-selected cell lines and patients samples have identified hybrid mRNAs comprised of an active, but apparently random, gene fused 5′ to MDR1. This observation indicates that random chromosomal rearrangements, such as translocations and inversions, leading to “capture” of MDR1 by constitutively expressed genes may be a mechanism for activation of this gene following drug exposure. In this study, fluorescence in situ hybridization (FISH) using whole chromosome paints (WCP) and bacterial artificial chromosome (BAC)-derived probes showed structural rearrangements involving 7q in metaphase and interphase cells, and comparative genomic hybridization (CGH) revealed high levels of amplification at chromosomal breakpoints. In an adriamycin-selected resistant colon cancer line (S48–3s/Adr), WCP4/WCP7 revealed t(4;7)(q31;q21) and BAC-derived probes demonstrated that the breakpoint lay between MDR1 and sequences 500–1000 KB telomeric to it. Similarly, in a subline isolated following exposure to actinomycin D (S48–3s/ActD), a hybrid MDR1 gene composed of heme oxygenase-2 sequences (at 16p13) fused to MDR1 was identified and a rearrangement confirmed with WCP7 and a subtelomeric 16p probe. Likewise, in a paclitaxel-selected MCF-7 subline where CASP sequences (at 7q22) were shown to be fused to MDR1, WCP7 showed an elongated chromosome 7 with a homogeneously staining regions (hsr); BAC-derived probes demonstrated that the hsr was composed of highly amplified MDR1 and CASP sequences. In all three selected cell lines, CGH demonstrated amplification at breakpoints involving MDR1(at 7q21) and genes fused to MDR1 at 4q31, 7q22, and 16p13.3. Finally, in samples obtained from two patients with drug refractory ALL, BAC-derived probes applied to archived marrow cells demonstrated that a breakpoint occurred between MDR1 and sequences 500–1000 KB telomeric to MDR1, consistent with a random chromosomal rearrangement. These results support the proposal that random chromosomal rearrangement leading to capture and activation of MDR1 is a mechanism of acquired drug resistance. Genes Chromosomes Cancer 23:44–54, 1998. © 1998 Wiley-Liss, Inc.     

One-Hour Rule-out and Rule-in of Acute Myocardial Infarction Using High-Sensitivity Cardiac Troponin T

BACKGROUND High-sensitivity cardiac troponin (hs-cTn) assays seem to improve the early diagnosis of acute myocardial infarction (AMI), but it is unknown how to best use them in clinical practice. Our objective was to develop and validate an algorithm for rapid rule-out and rule-in of AMI. METHODS A prospective multicenter study enrolling 872 unselected patients with acute chest pain presenting to the emergency department. High-sensitivity cardiac troponin T (hs-cTnT) was measured in a blinded fashion at presentation and after 1 hour. The final diagnosis was adjudicated by 2 independent cardiologists. An hs-cTnT algorithm incorporating baseline values as well as absolute changes within the first hour was derived from 436 randomly selected patients and validated in the remaining 436 patients. The primary prognostic end point was death during 30 days of follow-up. RESULTS Acute myocardial infarction was the final diagnosis in 17% of patients. After applying the hs-cTnT algorithm developed in the derivation cohort to the validation cohort, 259 patients (60%) could be classified as "rule-out," 76 patients (17%) as "rule-in," and 101 patients (23%) as in the "observational zone" within 1 hour. Overall, this resulted in a sensitivity and negative predictive value of 100% for rule-out, a specificity and positive predictive value of 97% and 84%, respectively, for rule-in, and a prevalence of AMI of 8% in the observational zone group. Cumulative 30-day survival was 99.8%, 98.6%, and 95.3% (P?<?.001) in patients classified as rule-out, observational zone, and rule-in, respectively. CONCLUSIONS Using a simple algorithm incorporating hs-cTnT baseline values and absolute changes within the first hour allowed a safe rule-out as well as an accurate rule-in of AMI within 1 hour in 77% of unselected patients with acute chest pain. This novel strategy may obviate the need for prolonged monitoring and serial blood sampling in 3 of 4 patients.     

Syndrome of short stature, mental deficiency, microcephaly, ectodermal dysplasia, and multiple skeletal anomalies

We report on two brothers with mental deficiency, short stature of prenatal onset, microcephaly, alopecia/sparse hair, follicular ichthyosis, multiple skeletal anomalies, and recurrent respiratory infections. The younger brother has celiac disease, cryptorchidism, inguinal herniae, and hypohidrosis, while the older brother has hidrotic ectodermal dysplasia, juvenile autoimmune thyroiditis, hypolacrimation, photophobia, and optic atrophy. Striking resemblance exists between our patients and those previously reported by Schinzel ?1980: Helv Paediatr Acta 35:243-251 and van Gelderen ?1982: Am J Med Genet 13:383-387. The fact that boys are born to young and healthy nonconsanguineous parents and there are no other affected relatives suggests autosomal or X-linked recessive inheritance or parental germinal mosaicism for a dominant mutation.     

Temporal modulation of spatial contrast vision in pigeons (Columba livia)

Spatiotemporal contrast sensitivity (CS) functions were obtained from four White Carneaux pigeons. The spatial frequency for each session was selected randomly from a group of five spatial frequencies ranging from 0.42 to 1.26 c/deg. Within the session, the temporal frequency varied from 1 to 32 Hz. When plotted as a function of spatial frequency, the CS functions peaked in the range 0.7-1.0 c/deg. When compared to data that had been collected at 0 Hz temporal modulation, the temporally modulated spatial CS functions showed reduced CS, especially at the higher spatial frequencies, and reduced peak spatial frequency. When plotted as a function of temporal frequency, the CS functions were flat up to 8-16 Hz. Above 16 Hz, the curves showed a sharp roll off. When plotted as a three-dimensional, spatiotemporal CS surface, the data had a number of characteristics in common with the three-dimensional spatiotemporal model of CS proposed by Burbeck and Kelly (J. Opt. Soc. Am. 70 (1980) 1121).     

Low or absent unconjugated estriol in pregnancy: an indicator for steroid sulfatase deficiency detectable by fluorescence in situ hybridization and biochemical analysis

It has been previously reported that a low or absent maternal serum unconjugated estriol (uE3) level is associated with placental steroid sulfatase (STS) deficiency. Here we report a correlation between patients who present with a very low or absent maternal serum uE3 and a deletion of the STS gene as assessed by fluorescence in situ hybridization (FISH). We studied nine prenatal cases that presented to the clinical laboratory with an abnormal triple screen, specifically low or absent maternal serum uE3 and a 46,XY karyotype. FISH analysis showed complete deletion of a probe containing the STS gene in six cases and one case had a partial deletion (reduced but not absent signal). The remaining two cases were not deleted for the STS probe. All mothers tested whose fetus showed a deletion were shown to be STS deletion carriers using FISH. Biochemical analysis was performed on 7/9 prenatal specimens. All fetuses deleted for the STS probe were also found to be deficient for STS by biochemical analysis of cultured amniotic fluid (5/5). Of the two fetuses not deleted for the STS probe, one was deficient for STS activity, while the other had a normal result. The abnormal result of enzyme deficiency by biochemical analysis in a non-deletion case likely represents a mutation in the STS gene, not detectable by this FISH assay. Postnatal FISH confirmation of the STS deletion was performed in 1/7 cases. Clinical follow-up was available for 4/9 cases following birth.     

A de novo PABPN1 germline mutation in a patient with oculopharyngeal muscular dystrophy

BACKGROUND: Oculopharyngeal muscular dystrophy (OPMD) is a late-onset autosomal dominantly inherited disorder characterized by dysphagia, ptosis, and proximal limb weakness and is caused by germline mutations (triplet repeat expansions) in the polyadenylate binding protein nuclear 1 (PABPN1) gene. OBJECTIVE: To describe a 70-year-old female patient with OPMD on the clinical and molecular genetic level and to develop a rapid and efficient molecular genetic screening method to study large patient groups. METHODS: Detailed family history and clinical assessment of the OPMD patient were followed by mutation analysis of the PABPN1 gene by direct DNA sequencing and by our newly developed method, fluorescent PABPN1 polymerase chain reaction (PCR) product (flPPP) method. A cohort of 50 healthy Swiss probands was screened using the flPPP to assess the frequency of the (GCG)7 allele in the Swiss population. Cricopharyngeal myotomy was performed as treatment for dysphagia. RESULTS: A heterozygous (GCG)9 triplet repeat expansion in PABPN1 was identified. Since the family history proved to be negative, the mutation is likely to have occurred de novo. The frequency of the (GCG)7 allele among healthy Swiss controls amounted to 1%. The flPPP method showed a sensitivity and specificity of 100%. Two years after cricopharyngeal myotomy, the patient is still relieved of dysphagia. CONCLUSIONS: An otolaryngologist should include OPMD in the differential diagnosis of a patient presenting with dysphagia, as this symptom can be the first sign of the disease and family history can be negative. Molecular genetic testing represents a highly accurate and rapid way to confirm the clinical diagnosis of OPMD. Cricopharyngeal myotomy relieves the patient of dysphagia in the majority of cases.