Recurrent De Novo NAHR Reciprocal Duplications in the ATAD3 Gene Cluster Cause a Neurogenetic Trait with Perturbed Cholesterol and Mitochondrial Metabolism

Adam C. Gunning, Klaudia Strucinska, Mikel Muñoz Oreja, Andrew Parrish, Richard Caswell, Karen L. Stals, Romina Durigon, Karina Durlacher-Betzer, Mitchell H. Cunningham, Christopher M. Grochowski, Julia Baptista, Carolyn Tysoe, Emma Baple, Nayana Lahiri, Tessa Homfray, Ingrid Scurr, Catherine Armstrong, John Dean, Uxoa Fernandez Pelayo, Aleck W.E. JonesRobert W. Taylor, Vinod K. Misra, Wan Hee Yoon, Caroline F. Wright, James R. Lupski, Antonella Spinazzola, Tamar Harel, Ian J. Holt, Sian Ellard

Research output: Contribution to journalArticlepeer-review

17 Scopus citations

Abstract

Recent studies have identified both recessive and dominant forms of mitochondrial disease that result from ATAD3A variants. The recessive form includes subjects with biallelic deletions mediated by non-allelic homologous recombination. We report five unrelated neonates with a lethal metabolic disorder characterized by cardiomyopathy, corneal opacities, encephalopathy, hypotonia, and seizures in whom a monoallelic reciprocal duplication at the ATAD3 locus was identified. Analysis of the breakpoint junction fragment indicated that these 67 kb heterozygous duplications were likely mediated by non-allelic homologous recombination at regions of high sequence identity in ATAD3A exon 11 and ATAD3C exon 7. At the recombinant junction, the duplication allele produces a fusion gene derived from ATAD3A and ATAD3C, the protein product of which lacks key functional residues. Analysis of fibroblasts derived from two affected individuals shows that the fusion gene product is expressed and stable. These cells display perturbed cholesterol and mitochondrial DNA organization similar to that observed for individuals with severe ATAD3A deficiency. We hypothesize that the fusion protein acts through a dominant-negative mechanism to cause this fatal mitochondrial disorder. Our data delineate a molecular diagnosis for this disorder, extend the clinical spectrum associated with structural variation at the ATAD3 locus, and identify a third mutational mechanism for ATAD3 gene cluster variants. These results further affirm structural variant mutagenesis mechanisms in sporadic disease traits, emphasize the importance of copy number analysis in molecular genomic diagnosis, and highlight some of the challenges of detecting and interpreting clinically relevant rare gene rearrangements from next-generation sequencing data.

Original languageEnglish
Pages (from-to)272-279
Number of pages8
JournalAmerican Journal of Human Genetics
Volume106
Issue number2
DOIs
StatePublished - Feb 6 2020

Keywords

  • ATAD3
  • ATAD3 gene cluster
  • Harel-Yoon
  • NAHR
  • cardiomyopathy
  • cholesterol
  • metabolic disorder
  • mitochondrial DNA
  • non-allelic homologous recombination

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