Genes associated with human microcephaly, a condition characterized by a small brain, include critical regulators of proliferation, cell fate and DNA repair. We describe a syndrome of congenital microcephaly and diverse defects in cerebral cortical architecture. Genome-wide linkage analysis in two families identified a 7.5-Mb locus on chromosome 19q13.12 containing 148 genes. Targeted high throughput sequence analysis of linked genes in each family yielded > 4,000 DNA variants and implicated a single gene, WDR62, as harboring potentially deleterious changes. We subsequently identified additional WDR62 mutations in four other families. Magnetic resonance imaging and postmortem brain analysis supports important roles for WDR62 in the proliferation and migration of neuronal precursors. WDR62 is a WD40 repeatĝ€"containing protein expressed in neuronal precursors as well as in postmitotic neurons in the developing brain and localizes to the spindle poles of dividing cells. The diverse phenotypes of WDR62 suggest it has central roles in many aspects of cerebral cortical development.
Bibliographical noteFunding Information:
We thank the many families and researchers who participated in this study; B. Chang and A. Poduri for expert review of MRI imaging findings; S. Lizarraga for contributions to genetic mapping; M. Aita and the In situ Hybridization Core Facility, University of North Carolina Neuroscience Center, Chapel Hill, North Carolina for performing in situ hybridizations; C.G. Woods for helpful discussions and for sharing data before publication; A. von Deimling from the Institut für Pathologie, Heidelberg, for sectioning of the LIS-2601 brain; A. Nicholas and M. Khurshid for advice regarding immunohistochemistry; A. Hill and L. Bu at the MRDDRC (Mental Retardation Developmental Disability Research Center) Imaging Core for assistance with confocal microscopy (US National Institutes of Health (NIH) grant P30-HD-18655 and Fidelity Foundation); and R. Sean Hill for assistance with linkage analysis and helpful discussions. We are indebted to the members of the Microcephaly Collaborative (Supplementary Table 1) for contributing to the cohort from which these families were drawn. T.W.Y. was supported by a NIH T32 grant (T32 NS007484-08), the Clinical Investigator Training Program (CITP) at Harvard-Massachusetts Institute of Technology Health Sciences and Technology and Beth Israel Deaconess Medical Center in collaboration with Pfizer, Inc. and Merck and Company, Inc., and the Nancy Lurie Marks Junior Faculty MeRIT Fellowship. G.H.M. was supported by the Young Investigator Award of National Alliance for Research on Schizophrenia and Depression (NARSAD) as a NARSAD Lieber Investigator. Research was supported by grants from the National Institute of Neurological Disorders and Stroke (NINDS) (RO1 NSR01-35129) and the Fogarty International Center (R21 NS061772) to C.A.W., the Dubai Harvard Foundation for Medical Research and the Manton Center for Orphan Disease Research. Genotyping services were provided by the Center for Inherited Disease Research (CIDR). CIDR is funded through a federal contract from the NIH to Johns Hopkins University, contract number HHSN268200782096C and NIH N01-HG-65403. Genotyping at Children’s Hospital Boston was supported by the Intellectual and Developmental Disabilities Research Centers (CHB DDRC, P30 HD18655). Genotyping at the Broad Institute was supported by National Human Genome Research Institute (NHGRI). C.A.W. is an investigator of the Howard Hughes Medical Institute.