@article {8316, title = {A multi-method approach to the molecular diagnosis of overt and borderline 11p15.5 defects underlying Silver-Russell and Beckwith-Wiedemann syndromes.}, journal = {Clin Epigenetics}, volume = {8}, year = {2016}, month = {2016}, pages = {23}, abstract = {

BACKGROUND: Multiple (epi)genetic defects affecting the expression of the imprinted genes within the 11p15.5 chromosomal region underlie Silver-Russell (SRS) and Beckwith-Wiedemann (BWS) syndromes. The molecular diagnosis of these opposite growth disorders requires a multi-approach flowchart to disclose known primary and secondary (epi)genetic alterations; however, up to 20 and 30~\% of clinically diagnosed BWS and SRS cases remain without molecular diagnosis. The complex structure of the 11p15 region with variable CpG methylation and low-rate mosaicism may account for missed diagnoses. Here, we demonstrate the relevance of complementary techniques for the assessment of different CpGs and the importance of testing multiple tissues to increase the SRS and BWS detection rate.

RESULTS: Molecular testing of 147 and 450 clinically diagnosed SRS and BWS cases provided diagnosis in 34 SRS and 185 BWS patients, with 9 SRS and 21 BWS cases remaining undiagnosed and herein referred to as "borderline." A flowchart including complementary techniques and, when applicable, the analysis of buccal swabs, allowed confirmation of the molecular diagnosis in all borderline cases. Comparison of methylation levels by methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA) in borderline and control cases defined an interval of H19/IGF2:IG-DMR loss of methylation that was distinct between "easy to diagnose" and "borderline" cases, which were characterized by values <=mean -3 standard deviations (SDs) compared to controls. Values >=mean +1 SD at H19/IGF2: IG-DMR were assigned to borderline hypermethylated BWS cases and those <=mean -2 SD at KCNQ1OT1: TSS-DMR to hypomethylated BWS cases; these were supported by quantitative pyrosequencing or Southern blot analysis. Six BWS cases suspected to carry mosaic paternal uniparental disomy of chromosome 11 were confirmed by SNP array, which detected mosaicism till 10~\%. Regarding the clinical presentation, borderline SRS were representative of the syndromic phenotype, with exception of one patient, whereas BWS cases showed low frequency of the most common features except hemihyperplasia.

CONCLUSIONS: A conclusive molecular diagnosis was reached in borderline methylation cases, increasing the detection rate by 6~\% for SRS and 5~\% for BWS cases. The introduction of complementary techniques and additional tissue analyses into routine diagnostic work-up should facilitate the identification of cases undiagnosed because of mosaicism, a distinctive feature of epigenetic disorders.

}, keywords = {Beckwith-Wiedemann Syndrome, Blotting, Southern, Child, Child, Preschool, Chromosomes, Human, Pair 11, CpG Islands, DNA Methylation, Epigenesis, Genetic, Female, Humans, Infant, Male, Mosaicism, Multiplex Polymerase Chain Reaction, Oligonucleotide Array Sequence Analysis, Silver-Russell Syndrome}, issn = {1868-7075}, doi = {10.1186/s13148-016-0183-8}, author = {Russo, Silvia and Calzari, Luciano and Mussa, Alessandro and Mainini, Ester and Cassina, Matteo and Di Candia, Stefania and Clementi, Maurizio and Guzzetti, Sara and Tabano, Silvia and Miozzo, Monica and Sirchia, Silvia and Finelli, Palma and Prontera, Paolo and Maitz, Silvia and Sorge, Giovanni and Calcagno, Annalisa and Maghnie, Mohamad and Divizia, Maria Teresa and Melis, Daniela and Manfredini, Emanuela and Ferrero, Giovanni Battista and Pecile, Vanna and Larizza, Lidia} } @article {7783, title = {Characterization of 14 novel deletions underlying Rubinstein-Taybi syndrome: an update of the CREBBP deletion repertoire.}, journal = {Hum Genet}, volume = {134}, year = {2015}, month = {2015 Jun}, pages = {613-26}, abstract = {

Rubinstein-Taybi syndrome (RSTS) is a rare, clinically heterogeneous disorder characterized by cognitive impairment and several multiple congenital anomalies. The syndrome is caused by almost private point mutations in the CREBBP (~55\% of cases) and EP300 (~8\%) genes. The CREBBP mutational spectrum is variegated and characterized by point mutations (30-50 \%) and deletions (~10\%). The latter are diverse in size and genomic position and remove either the whole CREBBP gene and its flanking regions or only an intragenic portion. Here, we report 14 novel CREBBP deletions ranging from single exons to the whole gene and flanking regions which were identified by applying complementary cytomolecular techniques: fluorescence in situ hybridization, multiplex ligation-dependent probe amplification and array comparative genome hybridization, to a large cohort of RSTS patients. Deletions involving CREBBP account for 23\% of our detected CREBBP mutations, making an important contribution to the mutational spectrum. Genotype-phenotype correlations revealed that patients with CREBBP deletions extending beyond this gene did not always have a more severe phenotype than patients harboring CREBBP point mutations, suggesting that neighboring genes play only a limited role in the etiopathogenesis of CREBBP-centerd contiguous gene syndrome. Accordingly, the extent of the deletion is not predictive of the severity of the clinical phenotype.

}, keywords = {Adolescent, Adult, Base Sequence, Child, Child, Preschool, Cohort Studies, CREB-Binding Protein, Female, Humans, Infant, Infant, Newborn, Male, Middle Aged, Point Mutation, Rubinstein-Taybi Syndrome, Sequence Deletion}, issn = {1432-1203}, doi = {10.1007/s00439-015-1542-9}, author = {Rusconi, Daniela and Negri, Gloria and Colapietro, Patrizia and Picinelli, Chiara and Milani, Donatella and Spena, Silvia and Magnani, Cinzia and Silengo, Margherita Cirillo and Sorasio, Lorena and Curtisova, Vaclava and Cavaliere, Maria Luigia and Prontera, Paolo and Stangoni, Gabriela and Ferrero, Giovanni Battista and Biamino, Elisa and Fischetto, Rita and Piccione, Maria and Gasparini, Paolo and Salviati, Leonardo and Selicorni, Angelo and Finelli, Palma and Larizza, Lidia and Gervasini, Cristina} } @article {8067, title = {Target sequencing approach intended to discover new mutations in non-syndromic intellectual disability.}, journal = {Mutat Res}, volume = {781}, year = {2015}, month = {2015 Nov}, pages = {32-6}, abstract = {

The technological improvements over the last years made considerable progresses in the knowledge of the etiology of intellectual Disability (ID). However, at present very little is known about the genetic heterogeneity underlying the non-syndromic form of ID (NS-ID). To investigate the genetic basis of NS-ID we analyzed 43 trios and 22 isolated NS-ID patients using a targeted sequencing (TS) approach. 71 NS-ID genes have been selected and sequenced in all subjects. We found putative pathogenic mutations in 7 out of 65 patients. The pathogenic role of mutations was evaluated through sequence comparison and structural analysis was performed to predict the effect of alterations in a 3D computational model through molecular dynamics simulations. Additionally, a deep patient clinical re-evaluation has been performed after the molecular results. This approach allowed us to find novel pathogenic mutations with a detection rate close to 11\% in our cohort of patients. This result supports the hypothesis that many NS-ID related genes still remain to be discovered and that NS-ID is a more complex phenotype compared to syndromic form, likely caused by a complex and broad interaction between genes alterations and environment factors.

}, issn = {1873-135X}, doi = {10.1016/j.mrfmmm.2015.09.002}, author = {Morgan, Anna and Gandin, Ilaria and Belcaro, Chiara and Palumbo, Pietro and Palumbo, Orazio and Biamino, Elisa and Dal Col, Valentina and Laurini, Erik and Pricl, Sabrina and Bosco, Paolo and Carella, Massimo and Ferrero, Giovanni Battista and Romano, Corrado and d{\textquoteright}Adamo, Adamo Pio and Faletra, Flavio and Vozzi, Diego} }