A total of 45 microsatellites (SSRs) were developed for mapping in Fragaria. They included 31 newly isolated codominant genomic SSRs from F. nubicola and a further 14 SSRs, derived from an expressed sequence tagged library (EST-SSRs) of the cultivated strawberry, F. x ananassa. These, and an additional 64 previously characterised but unmapped SSRs and EST-SSRs, were scored in the diploid Fragaria interspecific F2 mapping population (FVxFN) derived from a cross between F. vesca 815 and F. nubicola 601. The cosegregation data of these 109 SSRs, and of 73 previously mapped molecular markers, were used to elaborate an enhanced linkage map. The map is composed of 182 molecular markers (175 microsatellites, six gene specific markers and one sequence-characterised amplified region) and spans 424 cM over seven linkage groups. The average marker spacing is 2.3 cM/marker and the map now contains just eight gaps longer than 10 cM. The transferability of the new SSR markers to the cultivated strawberry was demonstrated using eight cultivars. Because of the transferable nature of these markers, the map produced will provide a useful reference framework for the development of linkage maps of the cultivated strawberry and for the development of other key resources for Fragaria such as a physical map. In addition, the map now provides a framework upon which to place transferable markers, such as genes of known function, for comparative mapping purposes within Rosaceae.

We propose an improved protocol for molecular testing for MJD. These strategies, developed to overcome the practical difficulties mostly in the presymptomatic and prenatal diagnosis of MJD, should prove useful for other polyglutamine-related disorders.

The identification of somatic driver mutations in cancer has enabled therapeutic advances by identifying drug targets critical to disease causation. However, such genomic discoveries in oncology have not translated into advances for non-cancerous disease since point mutations in a single cell would be unlikely to cause non-malignant disease. An exception to this would occur if the mutation happened early enough in development to be present in a large percentage of a tissue's cellular population. We sought to identify the existence of somatic mutations occurring early in human development by ascertaining base-pair mutations present in one of a pair of monozygotic twins, but absent from the other and assessing evidence for mosaicism. To do so, we genome-wide genotyped 66 apparently healthy monozygotic adult twins at 506 786 high-quality single nucleotide polymorphisms (SNPs) in white blood cells. Discrepant SNPs were verified by Sanger sequencing and a selected subset was tested for mosaicism by targeted high-depth next-generation sequencing (20 000-fold coverage) as a surrogate marker of timing of the mutation. Two de novo somatic mutations were unequivocally confirmed to be present in white blood cells, resulting in a frequency of 1.2×10(-7) mutations per nucleotide. There was little evidence of mosaicism on high-depth next-generation sequencing, suggesting that these mutations occurred early in embryonic development. These findings provide direct evidence that early somatic point mutations do occur and can lead to differences in genomes between otherwise identical twins, suggesting a considerable burden of somatic mutations among the trillions of mitoses that occur over the human lifespan.

Schwannomas are tumors arising from schwann cells surrounding peripheral nerves. Although most schwannomas are sporadic, they are seen in approximately 90% of individuals with neurofibromatosis type 2 (NF2), an autosomal dominantly inherited disease with an incidence of 1:40000 live births. The NF2 gene has recently been isolated on chromosome 22 and encodes a putative membrane organizing protein named schwannomin. It is believed to act as a tumor suppressor gene based on the high frequency of loss of heterozygosity (LOH) on this autosome in both sporadic and NF2 associated schwannomas and meningiomas and the identification of inactivating mutation in NF2 patients. In this study we examined 61 schwannomas including 48 sporadic schwannomas (46 of which are vestibular schwannomas) and 12 schwannomas obtained from NF2 patients, for mutations in 10 of the 16 coding exons of the NF2 gene. Twelve inactivating mutations were identified, 8 in sporadic tumours and 4 in tumors from people with NF2. These results support the hypothesis that loss of function of schwannomin is a frequent and fundamental event in the genesis of schwannomas.

Generalized epilepsy with febrile seizures plus (GEFS+) is a recently recognized but relatively common form of inherited childhood-onset epilepsy with heterogeneous epilepsy phenotypes. We genotyped 41 family members, including 21 affected individuals, to localize the gene causing epilepsy in a large family segregating an autosomal dominant form of GEFS+. A genomewide search examining 197 markers identified linkage of GEFS+ to chromosome 2, on the basis of an initial positive LOD score for marker D2S294 (Z=4.4, recombination fraction [straight theta] = 0). A total of 24 markers were tested on chromosome 2q, to define the smallest candidate region for GEFS+. The highest two-point LOD score (Zmax=5.29; straight theta=0) was obtained with marker D2S324. Critical recombination events mapped the GEFS+ gene to a 29-cM region flanked by markers D2S156 and D2S311, with the idiopathic generalized epilepsy locus thereby assigned to chromosome 2q23-q31. The existence of the heterogeneous epilepsy phenotypes in this kindred suggests that seizure predisposition determined by the GEFS+ gene on chromosome 2q could be modified by other genes and/or by environmental factors, to produce the different seizure types observed.