MICRO syndrome: an entity distinct from COFS syndrome

Children born with the findings of microcephaly, cataracts and microcornea can result not only from a prenatal viral infection, but also from an autosomal recessive Mendelian disorders. We present three pairs of affected siblings with MICRO syndrome, who were born with congenital microcephaly, microcornea, and cataracts. MICRO syndrome is an autosomal recessive syndrome consisting of congenital microcephaly, cortical dysplasia, microcornea, cataracts, optic atrophy, severe mental retardation, hypotonic diplegia, and hypogenitalism. At birth, MICRO syndrome resembles Cerebro-Oculo-Facio-Skeletal (COFS) syndrome, but it differs in the lack of the rapidly progressive neurologic features leading to severe brain atrophy with calcifications. Patients with MICRO syndrome manifest frontal cortical dysplasia, hypoplasia of the corpus callosum, cortical blindness with optic atrophy, profound mental retardation, and progressive joint contractures with growth failure. COFS syndrome shares also many clinical and cellular similarities with Cockayne syndrome (CS), and cultured cells in both conditions demonstrate hypersensitivity to ultraviolet (UV) radiation due to impaired nucleotide excision repair (NER). NER studies in cultured fibroblasts from MICRO patients give normal results, so MICRO syndrome should be considered in children with features resembling COFS syndrome and CS, but who have normal NER. MICRO should be distinguished from other similar clinical disorders with normal NER by the presence of significant visual impairment and cortical blindness despite early surgery for congenital cataracts, frontal polymicrogyria, thin corpus callosum, and cortical atrophy by MRI.