ZNF462 and KLF12 are disrupted by a de novo translocation in a patient with syndromic intellectual disability and autism spectrum disorder

Abstract

We describe a patient with a de novo balanced translocation 46,XY,t(9; 13)(q31.2; q22.1) and autism spectrum disorder, intellectual disability, a metopic craniosynostosis, a corpus callosum dysgenesis and dysmorphic facial features, most notably ptosis. Breakpoint mapping was performed by means of targeted locus amplification (TLA) and sequencing, because conventional breakpoint mapping by means of fluorescent in situ hybridization and long-range PCR was hampered by a complex submicroscopic rearrangement. The translocation breakpoints directly affected the genes KLF12 (chromosome 13) and ZNF462 (chromosome 9). The latter gene was disrupted by multiple breakpoints, resulting in the loss of three fragments and a rearrangement of the remaining fragments. Therefore, haploinsufficiency of ZNF462 was assumed. Loss-of-function variants in ZNF462 have recently been published by Weiss et al. (2017) in a series of eight patients from six independent families delineating the ZNF462-associated phenotype. The latter closely matches with the clinical features of the current translocation patient. Besides, no direct evidence for an association of KLF12 to the phenotypic features was found. Therefore, we conclude that the phenotype of the current patient is mainly caused by the disruption of ZNF462. We present clinical data from birth to adulthood and data on the cognitive and behavioral profile of the current patient which may add to a more precise counseling and surveillance of development in young children with ZNF462 mutations. In addition, the current case illustrates that TLA is an efficient method for determining complex chromosomal breakpoints.

Keywords: Corpus callosum; Craniosynostosis; Ptosis; Syndromic intellectual disability/autism spectrum disorder; Targeted locus amplification.