Oculomotility disorders arising from disruptions in brainstem motor neuron development

The identification and analysis of pedigrees with rare congenital oculomotility syndromes has led to the definition of the congenital cranial dysinnervation disorders. These disorders appear to result from mutations in genes that are essential to the normal development and/or connectivity of cranial motoneurons. This review highlights the clinical features and genetic etiology of 3 congenital cranial dysinnervation disorders: the human homeobox A1 (HOXA1) syndromes, in which early motoneuron development is disrupted; horizontal gaze palsy with progressive scoliosis, in which there is aberrant axonal targeting onto abducens motoneurons; and congenital fibrosis of the extraocular muscles type 1, in which there is aberrant axonal targeting onto the extraocular muscles.