Periodic alternating nystagmus in two children with a similar, unusual phenotype

The report describes two unrelated male children, aged 6 and 8 years, respectively, with congenital periodic alternating nystagmus, congenital strabismus, microcephaly with cortical and cerebellar hypoplasia, mental retardation, low stature, and bat ears. Karyotypes were normal. Neuropediatric and ophthalmologic examinations, radiologic imaging of the brain, and laboratory analyses were performed to exclude other causes of periodic alternating nystagmus, such as ataxia-telangiectasia, acquired disease of the caudal brainstem or the cerebellum, albinism, or loss of vision resulting from cataract or vitreous hemorrhage. The similar morphologic and clinical features of both patients raise the possibility that they have an identical syndrome.