Variants in SCAF4 Cause a Neurodevelopmental Disorder and Are Associated with Impaired mRNA Processing

Anna Fliedner, Philipp Kirchner, Antje Wiesener, Irma van de Beek, Quinten Waisfisz, Mieke van Haelst, Daryl A. Scott, Seema R. Lalani, Jill A. Rosenfeld, Mahshid S. Azamian, Fan Xia, Marina Dutra-Clarke, Julian A. Martinez-Agosto, Hane Lee, Grace J. Noh, Natalie Lippa, Anna Alkelai, Vimla Aggarwal, Katherine E. Agre, Ralitza GavrilovaGhayda M. Mirzaa, Rachel Straussberg, Rony Cohen, Brooke Horist, Vidya Krishnamurthy, Kirsty McWalter, Jane Juusola, Laura Davis-Keppen, Lisa Ohden, Marjon van Slegtenhorst, Stella A. de Man, Arif B. Ekici, Anne Gregor, Ingrid van de Laar, Christiane Zweier*, UCLA Clinical Genomics Center

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

RNA polymerase II interacts with various other complexes and factors to ensure correct initiation, elongation, and termination of mRNA transcription. One of these proteins is SR-related CTD-associated factor 4 (SCAF4), which is important for correct usage of polyA sites for mRNA termination. Using exome sequencing and international matchmaking, we identified nine likely pathogenic germline variants in SCAF4 including two splice-site and seven truncating variants, all residing in the N-terminal two thirds of the protein. Eight of these variants occurred de novo, and one was inherited. Affected individuals demonstrated a variable neurodevelopmental disorder characterized by mild intellectual disability, seizures, behavioral abnormalities, and various skeletal and structural anomalies. Paired-end RNA sequencing on blood lymphocytes of SCAF4-deficient individuals revealed a broad deregulation of more than 9,000 genes and significant differential splicing of more than 2,900 genes, indicating an important role of SCAF4 in mRNA processing. Knockdown of the SCAF4 ortholog CG4266 in the model organism Drosophila melanogaster resulted in impaired locomotor function, learning, and short-term memory. Furthermore, we observed an increased number of active zones in larval neuromuscular junctions, representing large glutamatergic synapses. These observations indicate a role of CG4266 in nervous system development and function and support the implication of SCAF4 in neurodevelopmental phenotypes. In summary, our data show that heterozygous, likely gene-disrupting variants in SCAF4 are causative for a variable neurodevelopmental disorder associated with impaired mRNA processing.

Original languageEnglish
Pages (from-to)544-554
Number of pages11
JournalAmerican journal of human genetics
Volume107
Issue number3
DOIs
Publication statusPublished - 3 Sep 2020

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