Phenotypic heterogeneity of genomic disorders and rare copy-number variants

Santhosh Girirajan, Jill A. Rosenfeld, Bradley P. Coe, Sumit Parikh, Neil Friedman, Amy Goldstein, Robyn A. Filipink, Juliann S. McConnell, Brad Angle, Wendy S. Meschino, Marjan M. Nezarati, Alexander Asamoah, Kelly E. Jackson, Gordon C. Gowans, Judith A. Martin, Erin P. Carmany, David W. Stockton, Rhonda E. Schnur, Lynette S. Penney, Donna M. MartinSalmo Raskin, Kathleen Leppig, Heidi Thiese, Rosemarie Smith, Erika Aberg, Dmitriy M. Niyazov, Luis F. Escobar, Dima El-Khechen, Kisha D. Johnson, Robert R. Lebel, Kiana Siefkas, Susie Ball, Natasha Shur, Marianne McGuire, Campbell K. Brasington, J. Edward Spence, Laura S. Martin, Carol Clericuzio, Blake C. Ballif, Lisa G. Shaffer, Evan E. Eichler

Research output: Contribution to journalArticlepeer-review

436 Scopus citations


BACKGROUND: Some copy-number variants are associated with genomic disorders with extreme phenotypic heterogeneity. The cause of this variation is unknown, which presents challenges in genetic diagnosis, counseling, and management. METHODS: We analyzed the genomes of 2312 children known to carry a copy-number variant associated with intellectual disability and congenital abnormalities, using array comparative genomic hybridization. RESULTS: Among the affected children, 10.1% carried a second large copy-number variant in addition to the primary genetic lesion. We identified seven genomic disorders, each defined by a specific copy-number variant, in which the affected children were more likely to carry multiple copy-number variants than were controls. We found that syndromic disorders could be distinguished from those with extreme phenotypic heterogeneity on the basis of the total number of copy-number variants and whether the variants are inherited or de novo. Children who carried two large copy-number variants of unknown clinical significance were eight times as likely to have developmental delay as were controls (odds ratio, 8.16; 95% confidence interval, 5.33 to 13.07; P = 2.11×10-38). Among affected children, inherited copy-number variants tended to co-occur with a second-site large copy-number variant (Spearman correlation coefficient, 0.66; P<0.001). Boys were more likely than girls to have disorders of phenotypic heterogeneity (P<0.001), and mothers were more likely than fathers to transmit second-site copy-number variants to their offspring (P = 0.02). CONCLUSIONS: Multiple, large copy-number variants, including those of unknown pathogenic significance, compound to result in a severe clinical presentation, and secondary copy-number variants are preferentially transmitted from maternal carriers. (Funded by the Simons Foundation Autism Research Initiative and the National Institutes of Health.)

Original languageEnglish (US)
Pages (from-to)1321-1331
Number of pages11
JournalNew England Journal of Medicine
Issue number14
StatePublished - Oct 4 2012

All Science Journal Classification (ASJC) codes

  • General Medicine


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