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Clinical exome sequencing has the potential to identify pathogenic variants unrelated to the purpose of the study (secondary findings, SFs). Data describing actual choices of SFs in participants in a clinical setting and factors influencing their decision are virtually non-existant in Europe. In this work, we report the acceptance rate of SFs, calculate their prevalence and study factors associated with the decision in a cohort of patients affected with a rare genetic disorder in a Spanish Hospital. Finally, we re-examine the presence of previously non reported family history in positive cases. We retrospectively reviewed informed consent choices and SF results from 824 unrelated probands affected with rare genetic disorders who underwent whole-genome or exome sequencing. Ninety percent of families (740/824) affected with rare disorders wished to be informed of SFs. Declining SFs was associated with a prenatal setting (30% vs. 8.7%, p = 0.025), consanguinity (19% vs. 8.7%, p = 0.013), male gender (10.6% vs. 1.5%, p = 0.00865) and the proband being a minor (10.6% vs. 1.5%, p = 0.014). Overall, 27 pathogenic or likely pathogenic variants were identified in 27 individuals, with an SF prevalence of 3.6%. Disclosure of SFs increased the percentage of positive family histories and resulted in early diagnosis or changes in the management of 10 individuals from five families. We show that the acceptance of SFs in Spain is high and the disclosure of SFs leads to a clinically meaningful change in the medical management of individuals.

Tatton-Brown-Rahman (TBRS) syndrome is a recently described overgrowth syndrome caused by loss of function variants in the DNMT3A gene. This gene encodes for a DNA methyltransferase 3 alpha, which is involved in epigenetic regulation, especially during embryonic development. Somatic variants in DNMT3A have been widely studied in different types of tumors, including acute myeloid leukemia, hematopoietic, and lymphoid cancers. Germline gain-of-function variants in this gene have been recently implicated in microcephalic dwarfism. Common clinical features of patients with TBRS include tall stature, macrocephaly, intellectual disability (ID), and a distinctive facial appearance. Differential diagnosis of TBRS comprises Sotos, Weaver, and Malan Syndromes. The majority of these disorders present other clinical features with a high clinical overlap, making necessary a molecular confirmation of the clinical diagnosis. We here describe seven new patients with variants in DNMT3A, four of them with neuropsychiatric disorders, including schizophrenia and psychotic behavior. In addition, one of the patients has developed a brain tumor in adulthood. This patient has also cerebral atrophy, aggressive behavior, ID, and abnormal facial features. Clinical evaluation of this group of patients should include a complete neuropsychiatric assessment together with psychological support in order to detect and manage abnormal behaviors such as aggressiveness, impulsivity, and attention deficit-hyperactivity disorder. TBRS should be suspected in patients with overgrowth, ID, tall stature, and macrocephaly, who also have some neuropsychiatric disorders without any genetic defects in the commonest overgrowth disorders. Molecular confirmation in these patients is mandatory., This project was supported by ISCII, FEDER funds grant: FIS-PI15/01481.

Contains fulltext : 168089.pdf (Publisher’s version ) (Open Access) Variants in the ZIC3 gene are rare, but have demonstrated their profound clinical significance in X-linked heterotaxy, affecting in particular male patients with abnormal arrangement of thoracic and visceral organs. Several reports have shown relevance of ZIC3 gene variants in both familial and sporadic cases and with a predominance of mutations detected in zinc-finger domains. No studies so far have assessed the functional consequences of ZIC3 variants in an in vivo model organism. A study population of 348 patients collected over more than 10 years with a large variety of congenital heart disease including heterotaxy was screened for variants in the ZIC3 gene. Functional effects of three variants were assessed both in vitro and in vivo in the zebrafish. We identified six novel pathogenic variants (1,7%), all in either male patients with heterotaxy (n=5) or a female patient with multiple male deaths due to heterotaxy in the family (n=1). All variants were located within the zinc-finger domains or leading to a truncation before these domains. Truncating variants showed abnormal trafficking of mutated ZIC3 proteins, whereas the missense variant showed normal trafficking. Overexpression of wild-type and mutated ZIC protein in zebrafish showed full non-functionality of the two frame-shift variants and partial activity of the missense variant compared with wild-type, further underscoring the pathogenic character of these variants. Concluding, we greatly expanded the number of causative variants in ZIC3 and delineated the functional effects of three variants using in vitro and in vivo model systems.