Complex neuropsychiatric-cardiac syndromes can be genetically determined. For the first time, the authors present a syndromal form of short QT syndrome in a 34-year-old German male patient with extracardiac features with predominant psychiatric manifestation, namely a severe form of secondary high-functioning autism spectrum disorder (ASD), along with affective and psychotic exacerbations, and severe dental enamel defects (with rapid wearing off his teeth) due to a heterozygous loss-of-function mutation in the CACNA1C gene (NM_000719.6: c.2399A > C; p.Lys800Thr). This mutation was found only once in control databases; the mutated lysine is located in the Cav1.2 calcium channel, is highly conserved during evolution, and is predicted to affect protein function by most pathogenicity prediction algorithms. L-type Cav1.2 calcium channels are widely expressed in the brain and heart. In the case presented, electrophysiological studies revealed a prominent reduction in the current amplitude without changes in the gating behavior of the Cav1.2 channel, most likely due to a trafficking defect. Due to the demonstrated loss of function, the p.Lys800Thr variant was finally classified as pathogenic (ACMG class 4 variant) and is likely to cause a newly described Cav1.2 channelopathy.

Marfan syndrome (MFS) is a hereditary connective tissue disease caused by heterozygous mutations in the fibrillin-1 gene (FBN1) located on chromosome 15q21.1. A complex chromosomal rearrangement leading to MFS has only been reported in one case so far. We report on a mother and daughter with marfanoid habitus and no pathogenic variant in the FBN1 gene after next generation sequencing (NGS) analysis, both showing a cytogenetically reciprocal balanced translocation between chromosomes 2 and 15. By means of fluorescence in situ hybridization of Bacterial artificial chromosome (BAC) clones from the breakpoint area on chromosome 15 the breakpoint was narrowed down to a region of approximately 110 kb in FBN1. With the help of optical genome mapping (OGM), the translocation breakpoints were further refined on chromosomes 2 and 15. Sequencing of the regions affected by the translocation identified the breakpoint of chromosome 2 as well as the breakpoint of chromosome 15 in the FBN1 gene leading to its disruption. To our knowledge, this is the first report of patients with typical clinical features of MFS showing a cytogenetically reciprocal translocation involving the FBN1 gene. Our case highlights the importance of structural genome variants as an underlying cause of monogenic diseases and the useful clinical application of OGM in the elucidation of structural variants.

Mutations in voltage-gated sodium channel (SCN) genes are supposed to be of importance in the etiology of psychiatric and neurological diseases, in particular in the etiology of seizures. Previous studies report a potential susceptibility region at the chromosomal locus 2q including SCN1A, SCN2A and SCN3A genes for autism spectrum disorder (ASD). To date, there is no previous description of a patient with comorbid ASD and Tourette syndrome showing a deletion containing SCN2A and SCN3A. We present the unique complex case of a 28-year-old male patient suffering from developmental retardation and exhibiting a range of behavioral traits since birth. He received the diagnoses of ASD (in early childhood) and of Tourette syndrome (in adulthood) according to ICD-10 and DSM-5 criteria. Investigations of underlying genetic factors yielded a heterozygous microdeletion of approximately 719 kb at 2q24.3 leading to a deletion encompassing the five genes SCN2A (exon 1 to intron 14–15), SCN3A, GRB14 (exon 1 to intron 2–3), COBLL1 and SCL38A11. We discuss the association of SCN2A, SCN3A, GRB14, COBLL1 and SCL38A11 deletions with ASD and Tourette syndrome and possible implications for treatment.

The CRISPR-Cas12a platform has attracted interest in the genome editing community because the prototypical Acidaminococcus Cas12a generates a staggered DNA double-strand break upon binding to an AT-rich protospacer-adjacent motif (PAM, 5′-TTTV). The broad application of the platform in primary human cells was enabled by the development of an engineered version of the natural Cas12a protein, called Cas12a Ultra. In this study, we confirmed that CRISPR-Cas12a Ultra ribonucleoprotein complexes enabled allelic gene disruption frequencies of over 90% at multiple target sites in human T cells, hematopoietic stem and progenitor cells (HSPCs), and induced pluripotent stem cells (iPSCs). In addition, we demonstrated, for the first time, the efficient knock-in potential of the platform in human iPSCs and achieved targeted integration of a GFP marker gene into the AAVS1 safe harbor site and a CSF2RA super-exon into CSF2RA in up to 90% of alleles without selection. Clonal analysis revealed bi-allelic integration in >50% of the screened iPSC clones without compromising their pluripotency and genomic integrity. Thus, in combination with the adeno-associated virus vector system, CRISPR-Cas12a Ultra provides a highly efficient genome editing platform for performing targeted knock-ins in human iPSCs.