Identification of a Recurrent Microdeletion at 17q23.1q23.2 Flanked by Segmental Duplications Associated with Heart Defects and Limb Abnormalities
AMERICAN JOURNAL OF HUMAN GENETICS
Authors: Ballif, Blake C.; Theisen, Aaron; Rosenfeld, Jill A.; Traylor, Ryan N.; Gastier-Foster, Julie; Thrush, Devon Lamb; Astbury, Caroline; Bartholomew, Dennis; McBride, Kim L.; Pyatt, Robert E.; Shane, Kate; Smith, Wendy E.; Banks, Valerie; Gallentine, William B.; Brock, Pamela; Rudd, M. Katharine; Adam, Margaret P.; Keene, Julia A.; Phillips, John A., III; Pfotenhauer, Jean P.; Gowans, Gordon C.; Stankiewicz, Pawel; Bejjani, Bassem A.; Shaffer, Lisa G.
Abstract
Segmental duplications, which comprise similar to 5%-10% of the human genome, are known to mediate medically relevant deletions, duplications, and inversions through nonallelic homologous recombination (NAHR) and have been suggested to be hot spots in chromosome evolution and human genomic instability. We report seven individuals with microdeletions at 17q23.1q23.2, identified by microarray-based comparative genomic hybridization (aCGH). Six of the seven deletions are similar to 2.2 Mb in size and flanked by large segmental duplications of >98% sequence identity and in the same orientation. One of the deletions is similar to 2.8 Mb in size and is flanked on the distal side by a segmental duplication, whereas the proximal breakpoint falls between segmental duplications. These characteristics suggest that NAHR mediated six out of seven of these rearrangements. These individuals have common features, including mild to moderate developmental delay (particularly speech delay), microcephaly, postnatal growth retardation, heart defects, and hand, foot, and limb abnormalities. Although all individuals had at least mild dysmorphic facial features, there was no characteristic constellation of features that would elicit clinical Suspicion of a specific disorder. The identification of common clinical features suggests that microdeletions at 17q23.1q23.2 constitute a novel syndrome. Furthermore, the inclusion in the minimal deletion region of TBX2 and TBX4, transcription factors belonging to a family of genes implicated in a variety of developmental pathways including those of heart and limb, suggests that these genes may play an important role in the phenotype of this emerging syndrome.
Stratification based on methylation of TBX2 and TBX3 into three molecular grades predicts progression in patients with pTa-bladder cancer
MODERN PATHOLOGY
Authors: Beukers, Willemien; Kandimalla, Raju; Masius, Roy G.; Vermeij, Marcel; Kranse, Ries; van Leenders, Geert J. L. H.; Zwarthoff, Ellen C.
Abstract
The potential risk of recurrence and progression in patients with non-muscle-invasive bladder cancer necessitates followup by cystoscopy. The risk of progression to muscle-invasive bladder cancer is estimated based on the European Organisation of Research and Treatment of Cancer score, a combination of several clinicopathological variables. However, pathological assessment is not objective and reproducibility is insufficient. The use of molecular markers could contribute to the estimation of tumor aggressiveness. We recently demonstrated that methylation of GATA2, TBX2, TBX3, and ZIC4 genes could predict progression in Ta tumors. In this study, we aimed to validate the markers in a large patient set using DNA from formalin-fixed and paraffin-embedded tissue. PALGA: the Dutch Pathology Registry was used for patient selection. We included 192 patients with pTaG1/2 bladder cancer of whom 77 experienced progression. Methylation analysis was performed and log-rank analysis was used to calculate the predictive value of each methylation marker for developing progression over time. This analysis showed better progression-free survival in patients with low methylation rates compared with the patients with high methylation rates for all markers (P<0.001) during a followup of ten-years. The combined predictive effect of the methylation markers was analyzed with the Cox-regression method. In this analysis, TBX2, TBX3, and ZIC4 were independent predictors of progression. On the basis of methylation status of TBX2 and TBX3, patients were divided into three new molecular grade groups. Survival analysis showed that only 8% of patients in the low molecular grade group progressed within 5 years. This was 29 and 63% for the intermediate-and high-molecular grade groups. In conclusion, this new molecular-grade based on the combination of TBX2 and TBX3 methylation is an excellent marker for predicting progression to muscle-invasive bladder cancer in patients with primary pTaG1/2 bladder cancer.