No evidence of locus heterogeneity in familial microcephaly with or without chorioretinopathy, lymphedema, or mental retardation syndrome.

Background: Microcephaly with or without chorioretinopathy, lymphedema, or mental retardation syndrome (MCLMR) is a rare autosomal dominant disorder with variable expressivity. It is characterized by mild-to-severe microcephaly, often associated with intellectual disability, ocular defects and lymphedema. It can be sporadic or inherited. Eighty-seven patients have been described to carry a mutation in, which encodes a homotetrameric KIF11 motor kinesin, EG5. Methods: We tested 23 unreported MCLMR index patients for . We also reviewed the clinical phenotypes of KIF11 all our patients as well as of those described in previously published studies. Results: We identified 14 mutations, 12 of which are novel. We detected mutations in 12 affected individuals, from 6 out of 6 familial cases, and in 8 out of 17 sporadic patients. Phenotypic evaluation of patients (our 26 + 61 earlier published = 87) revealed microcephaly in 91%, eye anomalies in 72%, intellectual disability in 67% and lymphedema in 47% of the patients. Unaffected carriers were rare (4 out of 87: 5%). Family history is not a requisite for diagnosis; 31% (16 out of 52) were cases. de novo Conclusions: All inherited cases, and 50% of sporadic cases of MCLMR are due to germline mutations. It is KIF11 possible that mosaic mutations cause the remainder of sporadic cases, which the methods employed here KIF11 were not designed to detect. On the other hand, some of them might have another mimicking disorder and genetic defect, as microcephaly is highly heterogeneous. In aggregate, mutations likely cause the majority, if KIF11 not all, of MCLMR. [ABSTRACT FROM AUTHOR]