Genomic analyses of patients with unexplained early onset scoliosis.

STUDY DESIGN To test for rare genetic mutations, a cohort of patients with unexplained early onset scoliosis (EOS) was screened using high-density microarray genotyping. A cohort of patients with adolescent idiopathic scoliosis (AIS) was similarly screened, and the results were compared. SUMMARY OF BACKGROUND DATA Patients with scoliosis in infancy or early childhood (EOS) are at high risk for progressive deformity and associated problems including respiratory compromise. EOS is frequently associated with genetic disorders, but many patients present with non-specific clinical features and without an associated diagnosis. We hypothesized that EOS in these patients may be caused by rare genetic mutations detectable by next-generation genomic methods. METHODS We ascertained 24 patients with unexplained EOS from pediatric orthopedic clinics. We genotyped them, along with 39 connecting family members, using the Illumina OmniExpress-12 v1.0 beadchip. Resulting genotypes were analyzed for chromosomal changes, specifically copy number variation (CNV) and absence of heterozygosity (AOH). We screened 482 AIS patients and 744 healthy controls, which were similarly genotyped with the same beadchip, for chromosomal changes identified in the EOS cohort. RESULTS Copy number variation (CNV) and absence of heterozygosity (AOH) analyses revealed a genetic diagnosis of chromosome 15q24 microdeletion syndrome in one patient, and maternal uniparental disomy of chromosome 14 in a second patient. Prior genetic testing and clinical evaluations had been negative in both cases. A large novel chromosome 10 deletion was likely causal in a third EOS patient. These mutations identified in the EOS patients were absent in AIS patients and controls, and thus not associated with AIS or found in asymptomatic individuals. CONCLUSIONS Our data underscore the utility of updated genetic evaluations including high-density microarray-based genotyping and other "next-generation" methods in patients with unexplained EOS, even where prior genetic studies were negative. These data also suggest the intriguing possibility that other mutations detectable by whole genome sequencing, as well as epigenetic effects, await discovery in the EOS population.