Oxford Nanopore long-read sequencing with CRISPR/Cas9-mediated target selection for accurate characterization of copy number variants in the LDLR gene.

Introduction: Familial hypercholesterolemia (FH) affects around 1 in 250 people. Most FH cases are caused by pathogenic LDLR variants, with copy number variations (CNVs) accounting for about 10 %. However, short-read gene panel sequencing and multiplex ligation-dependent probe amplification (MLPA) are limited in the specification of CNV breakpoints and the identification of complex structural variants (SVs).

Homozygous synonymous FAM111A variant underlies an autosomal recessive form of Kenny-Caffey syndrome.

FAM111A (family with sequence similarity 111 member A) is a serine protease and removes covalent DNA-protein cross-links during DNA replication. Heterozygous gain-of-function variants in FAM111A cause skeletal dysplasias, such as the perinatal lethal osteocraniostenosis and the milder Kenny-Caffey syndrome (KCS). We report two siblings born to consanguineous parents with dysmorphic craniofacial features, postnatal growth retardation, ophthalmologic manifestations, hair and nail anomalies, and skeletal abnormalities such as thickened cortex and stenosis of the medullary cavity of the long bones suggestive of KCS.