New resources for genetic studies in Populus nigra: genome-wide SNP discovery and development of a 12k Infinium array.

Whole genome resequencing of 51 Populus nigra (L.) individuals from across Western Europe was performed using Illumina platforms. A total number of 1 878 727 SNPs distributed along the P. nigra reference sequence were identified. The SNP calling accuracy was validated with Sanger sequencing. SNPs were selected within 14 previously identified QTL regions, 2916 expressional candidate genes related to rust resistance, wood properties, water-use efficiency and bud phenology and 1732 genes randomly spread across the genome. Over 10 000 SNPs were selected for the construction of a 12k Infinium Bead-Chip array dedicated to association mapping. The SNP genotyping assay was performed with 888 P. nigra individuals. The genotyping success rate was 91%. Our high success rate was due to the discovery panel design and the stringent parameters applied for SNP calling and selection. In the same set of P. nigra genotypes, linkage disequilibrium throughout the genome decayed on average within 5-7 kb to half of its maximum value. As an application test, ADMIXTURE analysis was performed with a selection of 600 SNPs spread throughout the genome and 706 individuals collected along 12 river basins. The admixture pattern was consistent with genetic diversity revealed by neutral markers and the geographical distribution of the populations. These newly developed SNP resources and genotyping array provide a valuable tool for population genetic studies and identification of QTLs through natural-population based genetic association studies in P. nigra.

The isochromosome i(7)(q10) carrying c.258+2t>c mutation of the SBDS gene does not promote development of myeloid malignancies in patients with Shwachman syndrome.

Shwachman-Diamond syndrome (SDS) is an autosomal recessive disorder, characterized by exocrine pancreatic insufficiency, skeletal abnormalities and bone marrow (BM) dysfunction with an increased risk to develop myelodysplastic syndrome and/or acute myeloid leukaemia (MDS/AML). SDS is caused, in nearly 90% of cases, by two common mutations (that is, c.183_184TA>CT and c.258+2T>C) in exon 2 of the SBDS gene, localized on chromosome 7. Clonal chromosome anomalies are often found in the BM of SDS patients; the most frequent is an isochromosome for long arms of chromosome 7, i(7)(q10). We studied eight patients with SDS carrying the i(7)(q10) who were compound heterozygotes for SBDS mutations. By assessing the parental origin of the i(7)(q10) using microsatellite analysis, we inferred from the results which mutation was present in double dose in the isochromosome. We demonstrate that in all cases the i(7)(q10) carries a double dose of the c.258+2T>C, and we suggest that, as the c.258+2T>C mutation still allows the production of some amount of normal protein, this may contribute to the low incidence of MDS/AML in this subset of SDS patients.

Role of radio-guided surgery in recurrent secondary hyperparathyroidism.

BACKGROUND: The aim of this paper is to state the role of radio-guided surgery (RGS) in case of recurrent secondary hyperparathyroidism. METHODS: Two cases of recurrent secondary hyperparathyroidism were treated using RGS. After a preoperative assessment, which included ultrasonography (US), MRI and (99m)Tc-radiolabelled sestamibi scan, a radio-guided neck re-exploration was planned. On the day of surgery the patients underwent a radionuclide injection. After 90 min, surgery began. RESULTS: Dissection was guided by placing the probe in the wound to localize any increased concentration of radioactivity. In the first case the probe identified the gland located deeply in the right tracheo-esophageal groove; in the other case the probe detected a site of increased uptake in the upper mediastinum. Both lesions were dissected and excised; a frozen section confirmed they were parathyroid glands with diffuse hyperplasia. The operative time was less than 60 min in both cases. The patients were discharged on the first postoperative day. A decrease in serum calcium and PTH was observed subsequently. A minimum follow-up of 6 months did not show any recurrence. CONCLUSION: RGS can help in detecting the parathyroid tissue in selected cases of renal hyperparathyroidism and makes operation much easier and more predictable.