SELNET clinical practice guidelines for bone sarcoma

Bone sarcoma are infrequent diseases, representing < 0.2% of all adult neoplasms. A multidisciplinary management within reference centers for sarcoma, with discussion of the diagnostic and therapeutic strategies within an expert multidisciplinary tumour board, is essential for these patients, given its heterogeneity and low frequency. This approach leads to an improvement in patient's outcome, as demonstrated in several studies. The Sarcoma European Latin-American Network (SELNET), aims to improve clinical outcome in sarcoma care, with a special focus in Latin-American countries. These Clinical Practice Guidelines (CPG) have been developed and agreed by a multidisciplinary expert group (including medical and radiation oncologist, surgical oncologist, orthopaedic surgeons, radiologist, pathologist, molecular biologist and representatives of patients advocacy groups) of the SELNET consortium, and are conceived to provide the standard approach to diagnosis, treatment and follow-up of bone sarcoma patients in the Latin-American context.

A high prevalence of biallelic RPE65 mutations in Costa Rican children with Leber congenital amaurosis and early-onset retinal dystrophy

BACKGROUND

Leber congenital amaurosis (LCA) and early-onset retinal dystrophy (EORD), are primary causes of inherited childhood blindness. Both are autosomal recessive diseases, with mutations in more than 25 genes explaining approximately ~70% of cases. However, the genetic cause for many cases remains unclear. Sequencing studies from genetically isolated populations with increased prevalence of a disorder has proven useful for rare variant studies, making Costa Rica an ideal place to study LCA/EORD genetics.

MATERIALS AND METHODS

Twenty-eight affected children (25 LCA, three EORD) and their immediate family members, totaling 52 individuals (30 affected) from 22 families, were sequenced. Whole exome sequencing was performed on all affected individuals. Available parents were analyzed either by whole exome sequencing (WES) or Sanger sequencing to determine transmission.

RESULTS

All affected individuals demonstrated compound heterozygous or homozygous mutations in known Inherited Retinal Disease (IRD) associated genes. Twelve variants were identified in at least one individual in three genes, RDH12, RPE65, and USH2A. Four recurrent RPE65 mutations were observed in 97% of individuals and 95% of families. All patients with LCA and two of the three individuals with EORD had biallelic mutations in RPE65; one child with EORD had a homozygous RDH12 mutation.

CONCLUSIONS

These data suggest that the majority of LCA/EORD in Costa Rica is due to four founder mutations in RPE65 which have been maintained in this genetically isolated population. This finding is of great clinical significance due to the availability of gene therapy recently approved in the US and European Union for patients with biallelic RPE65 defects.

PCR-RFLP identification of endemic Chilean species of Rhagoletis (Diptera: Tephritidae) attacking Solanaceae

Four species of the genus Rhagoletis are native to Chile: R. nova (Schiner), R. conversa, (Brèthes), R. penela Foote and R. tomatis Foote. Currently, identification of these species is based on morphological criteria, but their strong similarity makes precise recognition difficult. To clarify species separation for quarantine purposes, a reliable method based on a PCR-RFLP procedure is reported. A DNA region containing mitochondrial NADH dehydrogenase genes was selected as a target sequence for the analysis. The amplification products (c. 1 kb) were digested with either SspI or DdeI, yielding specific patterns that differentiated each of the endemic species. Complete nucleotide sequences were determined, confirming empirical restriction maps. This report updates information on the geographical distribution of Rhagoletis species in Chile.

First Report of Potato Spindle Tuber Viroid in Costa Rica

During 1997 to 1998, symptoms of leaf roll, dwarfism, chlorosis, and occasional leaf necrosis were observed on Solanum tuberosum in several plots in Cartago, the principal potato-production region of Costa Rica. Because of the known association between potato leafroll virus (PLRV) and viroids (1) and previous reports of PLRV in Costa Rica, the presence of potato spindle tuber viroid (PSTVd) was suspected. Leaf samples from 122 symptomatic potato plants, cvs. Atzimba, Floresta, Idiafrit, and Birris, were collected from 10 plots. Total nucleic acids (TNAs) were extracted and purified (2) from collected symptomatic samples and six healthy potato controls. TNAs were spotted on nylon membranes and hybridized to a digoxigenin-labeled DNA probe specific for PSTVd. Of 122 symptomatic plants, 71 were positive for PSTVd based on dot blot hybridization. TNAs from 12 positive potato samples, including at least 1 sample from each cultivar, were used to inoculate Lycopersicum esculentum cv. Super Marmande. Eleven of twelve inoculated tomato plants showed symptoms of dwarfism, leaf deformation, and grayish foliage, often with a dull surface. TNAs were extracted from inoculated tomato and hybridized to the PSTVd probe. All inoculated symptomatic plants were positive for PSTVd based on dot blot hybridization. This is the first report of PSTVd in Costa Rica. References: (1) M. Querci et al. J. Gen. Virol. 78:1207, 1997. (2) W. Villalobos et al. Rev. Biol. Trop. 45:983, 1997.