Machado-Joseph disease (MJD) is an autosomal dominantly-inherited neurodegenerative disorder, caused by an over-repetition of the polyglutamine-codifying region in the ATXN3 gene. Strategies based on the suppression of the deleterious gene products have demonstrated promising results in pre-clinical studies. Nonetheless, these strategies do not target the root cause of the disease. In order to prevent the downstream toxic pathways, our goal was to develop gene editing-based strategies to permanently inactivate the human ATXN3 gene. TALENs and CRISPR-Cas9 systems were designed to target exon 2 of this gene and functional characterization was performed in a human cell line. After the demonstration of TALEN and CRISPR-Cas9 efficiency on gene disruption, a sequence of each system was selected for further in vivo experiments. Although both TALENs and CRISPR-Cas9 systems led to a drastic reduction of ATXN3 aggregates in the striatum of a lentiviral-based mouse model of MJD/SCA3, only CRISPR-Cas9 system allowed the improvement of key neuropathological markers of the disease. Importantly, the administration of the engineered system in YAC-MJD84.2/84.2 mice mediated a delay in disease progression, when compared with non-treated littermates. These data provide the first in vivo evidence of the efficacy of a CRISPR-Cas9-based approach to permanently inactivate the ATXN3 gene in the brain of two mouse models of the disease, supporting its potential as a new therapeutic avenue in the context of MJD/SCA3. ### Competing Interest Statement N.E.S. is an adviser to Qiagen and a cofounder and adviser of TruEdit Bio and OverT Bio. P.D.H. acknowledges outside interest in Terrain Biosciences, Stylus Medicine, Spotlight Therapeutics, Arbor Biosciences, Varda Space, Vial Health, and Veda Bio, where he holds various roles including as co-founder, director, scientific advisory board member, or consultant.

Blepharophimosis with intellectual disability (BIS) is a recently recognized disorder distinct from Nicolaides-Baraister syndrome that presents with distinct facial features of blepharophimosis, developmental delay, and intellectual disability. BIS is caused by pathogenic variants in SMARCA2, that encodes the catalytic subunit of the superfamily II helicase group of the BRG1 and BRM-associated factors (BAF) forming the BAF complex, a chromatin remodeling complex involved in transcriptional regulation. Individuals bearing variants within the bipartite nuclear localization (BNL) signal domain of ADNP present with the neurodevelopmental disorder known as Helsmoortel-Van Der Aa Syndrome (HVDAS). Distinct DNA methylation profiles referred to as episignatures have been reported in HVDAS and BAF complex disorders. Due to molecular interactions between ADNP and BAF complex, and an overlapping craniofacial phenotype with narrowing of the palpebral fissures in a subset of patients with HVDAS and BIS, we hypothesized the possibility of a common phenotype-specific episignature. A distinct episignature was shared by 15 individuals with BIS-causing SMARCA2 pathogenic variants and 12 individuals with class II HVDAS caused by truncating pathogenic ADNP variants. This represents first evidence of a sensitive phenotype-specific episignature biomarker shared across distinct genetic conditions that also exhibit unique gene-specific episignatures.

BACKGROUND:Familial Adenomatous Polyposis (FAP) is a colorectal cancer (CRC) predisposition syndrome caused by germline APC mutations and characterised by an increased risk of CRC and colonic polyps and, in certain forms, of specific prominent extraintestinal manifestations, namely osteomas, soft tissue tumours and dental anomalies. Pachydysostosis of the fibula is a rare clinical entity defined by unilateral bowing of the distal portion of the fibula and elongation of the entire bone, without affectation of the tibia.CLINICAL REPORT:We report a 17-year-old male, who presented with a non-progressive bowing of the right leg detected at 18 months of age caused by a fibula malformation (later characterized as pachydysostosis) and a large exophytic osteoma of the left radius, noticed at the age of 15 years, without gastrointestinal symptoms. There was no relevant family history. Detailed characterisation revealed multiple osteomas, skin lesions and dental abnormalities, raising the hypothesis of FAP. This diagnosis was confirmed by genetic testing [c.4406_4409dup p.(Ala1471Serfs*17) de novo mutation in the APC gene] and endoscopic investigation (multiple adenomas throughout the colon, ileum and stomach).DISCUSSION:This case report draws attention to the phenotypic spectrum of skeletal manifestations of FAP: this patient has a congenital fibula malformation, not previously associated with this syndrome, but which is likely to have been its first manifestation in this patient. This clinical case also illustrates the challenges in the early diagnosis of FAP, especially without family history, and highlights the importance of a multidisciplinary approach and the adequate study of rare skeletal abnormalities.

BACKGROUND:Risk-reducing surgeries are an option for cancer risk management in BRCA1/2 individuals. However, while adnexectomy is commonly recommended in breast cancer (BC) survivors, risk-reducing bilateral breast surgery (RRBBS) is controversial in ovarian cancer (OC) survivors due to relapse rates and mortality.METHODS:We conducted a retrospective analysis of BRCA1/2-OC survivors, with OC as first cancer diagnosis.RESULTS:Median age at OC diagnosis for the 69 BRCA1/2-OC survivors was 54 years. Median overall survival was 8 years, being significantly higher for BRCA2 patients than for BRCA1 patients (p = 0.011). Nine patients (13.2%) developed BC at a median age of 61 years. The mean overall BC-free survival was 15.5 years (median not reached). Eight patients (11.8%) underwent bilateral mastectomy (5 simultaneous with BC treatment; 3 RRBBS) at a median age of 56.5 years. The median time from OC to bilateral mastectomy/RRBBS was 5.5 years.CONCLUSIONS:This study adds evidence regarding a lower BC risk after BRCA1/2-OC and higher survival for BRCA2-OC patients. A comprehensive analysis of the competing risks of OC mortality and recurrence against the risk of BC should be individually addressed. Surgical BC risk management may be considered for longer BRCA1/2-OC disease-free survivors. Ultimately, these decisions should always be tailored to patients' characteristics and preferences.