Detection of the Philadelphia chromosome in acute lymphoblastic leukemia by pulsed-field gel electrophoresis

The Philadelphia (Ph1) chromosome is an acquired abnormality in the malignant cells of 10% to 25% of patients with acute lymphoblastic leukemia (ALL). Unlike chronic myelogenous leukemia (CML), where the molecular detection of the Ph1 chromosome is relatively straightforward using conventional Southern hybridization analysis, the detection of the Ph1 chromosome in ALL is complicated by the existence of several molecular subtypes, and the fact that translocation breakpoints are dispersed over a large genomic area. To circumvent these difficulties, we investigated pulsed-field gel electrophoresis (PFGE) to determine if this method could be used directly on clinical samples to detect the Ph1 chromosome in ALL. We report that, in a study of seven patients with Ph1-positive ALL, we could easily detect the Ph1 using only a single PFGE analysis, regardless of the Ph1 subtype, and we could confirm that the translocations occur either within or very near the BCR gene in all seven. We conclude that PFGE is a useful technique for the detection of the Ph1 in ALL, which ultimately may find wide applicability in the detection of other chromosomal abnormalities in other malignancies.     

Immunosuppression in renal transplantation: Long-term clinical trial of a double versus triple therapy regimen

Summary: Sixty-nine renal allograft recipients were randomized to two immunosuppressive regimens: 35 patients received cyclosporine A and prednisolone (PC) while 34 patients received low dose cyclosporine A, prednisolone and short term azathioprine (PCA). the data of 66 patients (34 in PC and 32 in PCA groups) were analysed. the median follow-up periods were 62 months for the PC group and 60 months for the PCA group. There was no difference in graft survival between the two groups but five patients died in the PC group compared to none in the PCA group (graft survival: 88 vs 90% at 1 year and 82 vs 82% at 5 years, P = not significant at any time point; patient survival: 90 vs 100% at 1 year and 88 vs 100% at 5 years, P = 0.05 at 5 years). There was a trend for patients in the PCA group to develop earlier and more frequent rejections (not significant; P = 0.106 and P = 0.062, respectively). There were also more episodes of acute cyclosporine A nephrotoxicity and cytomegalovirus (CMV) infection in the PC group. the mean serum creatinine at 5 years was significantly higher in the PCA group when compared to the PC group (179.8 ± 76.5 μmol/L vs 154.7 ± 41.0 μmol/L; P =0.05). We found that both therapeutic regimens were effective in preventing renal allograft rejections. However, double therapy was associated with higher patient mortality secondary to infection. Patients on triple therapy, on the other hand, were more prone to develop rejections in the early post-transplant period and were associated with less favourable renal function in the long run.     

Malignant hereditary paraganglioma: problems raised by non-functional forms management

Non-functional paraganglioma have not clinical or biological characteristics, so that the diagnostic is most of the time delayed and made on the occasion of advanced abdominal tumor or symptomatic metastasis management. Hereditary forms, notably those with SDHB mutation, seem to have a poor prognosis. On the other hand, and on the oposite to sporadic forms, they are the only ones to benefit from genetic testing which make possible, if positive, an earlier diagnostic, before apparition of symptoms, recurrence or metastasis. We report a case of non-functional malignant hereditary paraganglioma diagnosed belatedly and we will consider management problems raised by non-functional forms.     

Spectrum of mutations in Gitelman syndrome

Gitelman's syndrome (GS) is a rare, autosomal recessive, salt-losing tubulopathy caused by mutations in the SLC12A3 gene, which encodes the thiazide-sensitive NaCl cotransporter (NCC). Because 18 to 40% of suspected GS patients carry only one SLC12A3 mutant allele, large genomic rearrangements may account for unidentified mutations. Here, we directly sequenced genomic DNA from a large cohort of 448 unrelated patients suspected of having GS. We found 172 distinct mutations, of which 100 were unreported previously. In 315 patients (70%), we identified two mutations; in 81 patients (18%), we identified one; and in 52 patients (12%), we did not detect a mutation. In 88 patients, we performed a search for large rearrangements by multiplex ligation-dependent probe amplification (MLPA) and found nine deletions and two duplications in 24 of the 51 heterozygous patients. A second technique confirmed each rearrangement. Based on the breakpoints of seven deletions, nonallelic homologous recombination by Alu sequences and nonhomologous end-joining probably favor these intragenic deletions. In summary, missense mutations account for approximately 59% of the mutations in Gitelman's syndrome, and there is a predisposition to large rearrangements (6% of our cases) caused by the presence of repeated sequences within the SLC12A3 gene.     

Clinical and molecular genetics of patients with the Carney-Stratakis syndrome and germline mutations of the genes coding for the succinate dehydrogenase subunits SDHB, SDHC, and SDHD

Gastrointestinal stromal tumors (GISTs) may be caused by germline mutations of the KIT and platelet-derived growth factor receptor-alpha (PDGFRA) genes and treated by Imatinib mesylate (STI571) or other protein tyrosine kinase inhibitors. However, not all GISTs harbor these genetic defects and several do not respond to STI571 suggesting that other molecular mechanisms may be implicated in GIST pathogenesis. In a subset of patients with GISTs, the lesions are associated with paragangliomas; the condition is familial and transmitted as an autosomal-dominant trait. We investigated 11 patients with the dyad of 'paraganglioma and gastric stromal sarcoma'; in eight (from seven unrelated families), the GISTs were caused by germline mutations of the genes encoding subunits B, C, or D (the SDHB, SDHC and SDHD genes, respectively). In this report, we present the molecular effects of these mutations on these genes and the clinical information on the patients. We conclude that succinate dehydrogenase deficiency may be the cause of a subgroup of GISTs and this offers a therapeutic target for GISTs that may not respond to STI571 and its analogs.     

First experience with robotic pancreatoduodenectomy in Singapore

INTRODUCTIONRecent studies reported that laparoscopic pancreatoduodenectomy (LPD) is associated with superior perioperative outcomes compared to the open approach. However, concerns have been raised about the safety of LPD, especially during the learning phase. Robotic pancreatoduodenectomy (RPD) has been reported to be associated with a shorter learning curve compared to LPD. We herein present our initial experience with RPD.METHODSA retrospective review of a single-institution prospective robotic hepatopancreaticobiliary (HPB) surgery database of 70 patients identified seven consecutive RPDs performed by a single surgeon in 2016–2017. These were matched at a 1:2 ratio with 14 open pancreatoduodenectomies (OPDs) selected from 77 consecutive pancreatoduodenectomies performed by the same surgeon between 2011 and 2017.RESULTSSeven patients underwent RPD, of which five were hybrid procedures with open reconstruction. There were no open conversions. Median operative time was 710.0 (range 560.0–930.0) minutes. Two major morbidities (> Grade 2) occurred: one gastrojejunostomy bleed requiring endoscopic haemostasis and one delayed gastric emptying requiring feeding tube placement. There were no pancreatic fistulas, reoperations or 90-day/in-hospital mortalities in the RPD group. Comparison between RPD and OPD demonstrated that RPD was associated with a significantly longer operative time. Compared to open surgery, there was no significant difference in estimated blood loss, blood transfusion, postoperative stay, pancreatic fistula rates, morbidity and mortality rates, R0 resection rates, and lymph node harvest rates.CONCLUSIONOur initial experience demonstrates that RPD is feasible and safe in selected patients. It can be safely adopted without any compromise in patient outcomes compared to the open approach.