Agyria--pachygyria and Miller-Dieker syndrome: clinical, genetic and chromosome studies

Genetic factors in lissencephaly syndromes: a review

Lissencephaly is a sign of various genetic and non-genetic conditions and a constant feature in the so-called lissencephaly syndromes. Type I lissencephaly in the Miller-Dieker syndrome (MDS) and the isolated lissencephaly sequence (ILS) is differentiated from type II lissencephaly in the Walker-Warburg (hydrocephalus, agyria, retinal dysplasia with or without encephalocele, HARD +/- E) syndrome and related conditions (e.g. muscle-eye-brain syndrome). In about 90% of patients with MDS structural defects have been confirmed in the short arm of chromosome 17 (p13.3), detectable by classical cytogenetic methods, fluorescence in situ hybridisation (FISH), or molecular genetic techniques. The identification of unbalanced inversions and translocations is of particular importance because of the risk of their recurrence, while deletions and ring chromosomes are mainly sporadic. Recently, submicroscopic deletions have also been reported in ILS, providing evidence that lissencephaly in MDS and ILS is caused by deletions of the same gene(s) in 17p13.3 and that MDS may be considered to be a "contiguous gene syndrome." Syndromes featuring lissencephaly type II (HARD +/- E and related conditions) are most probably autosomal-recessively inherited. Neither the location of the genes involved nor the nature of the mutations are known at present. It is also unknown whether HARD +/- E and muscle-eye-brain syndrome are allelic.

Alpers progressive infantile neuronal poliodystrophy: an acute neonatal form with findings of the fetal akinesia syndrome

We report on 8 patients from two families with Alpers syndrome. The onset in one family was prenatal and in the 4 patients who were examined, severe microcephaly, intrauterine growth retardation, and typical manifestations of fetal akinesia, including retrognathia, joint limitations, and chest deformity were found. The second family presented with an early infantile form. All the affected offspring had micrognathia and one had findings of fetal akinesia, comparable to those seen in the other family. Microcephaly was mild at birth and progressed with age. Refractory neonatal convulsions, swallowing difficulties, and pneumonia complicated the clinical course of patients in both families, and all the patients died before age 20 months. Results of comprehensive biochemical and metabolic studies in both families were normal and the diagnosis was supported by demonstration of extensive progressive brain atrophy on CT and typical histological findings. Patients without a detectable defect in energy metabolism and normal liver histology comprise a distinct subset of Alpers syndrome. Until the metabolic defect(s) is defined, we suggest naming the acute neonatal form of this subset of Alpers syndrome "type 1."

Structure in lissencephaly determined by immunohistochemical staining

The brains of patients with lissencephaly were examined by peroxidase-antiperoxidase immunohistochemical staining of synaptophysin, myelin basic protein, and glial fibrillary acidic protein. In contrast to the normal cortical pattern, the cortex, with a smooth surface, demonstrated quite different staining patterns in the molecular, superficial cellular, sparsely cellular, and deep cellular layers. The molecular layer was abnormally positive with synaptophysin staining. The superficial cellular layer was also diffusely stained for synaptophysin; there was a positive reaction in the linearly arranged myelin sheaths. The sparsely cellular layer revealed less staining for synaptophysin, but was perivascularly positive for glial fibrillary acidic protein. In the deep cellular layer, synaptophysin staining had multiple neuronal columns and myelin basic protein-staining had a reticular pattern around neuronal columns. These results suggest that the sparsely cellular layer may correspond to the molecular layer and white matter in normal brain; neurons with forming myelin sheaths in the superficial cellular layer regularly penetrate the surface of the molecular layer, forming arrested cortical columns in the deep cellular layer.

Diagnostic features and clinical signs of 21 patients with lissencephaly type 1

Lissencephaly type I has been described as either the cerebral expression of a complex malformation syndrome such as Miller-Dieker syndrome (MDS), or as isolated lissencephaly sequence (ILS). In a nation-wide study in The Netherlands, of 21 patients with lissecephaly type I, four were found to have MDS and 17 ILS. New clinical aspects were as follows: the mean life-span of the entire group was longer than previously reported; patients with lissencephaly grades 3 or 4 (mixture of agyria and pachygyria, or complete pachygyria) developed seizures later than those with grades 1 and 2 (complete and almost complete agyria); microcephaly was not always present in patients with grades 3 and 4 lissencephaly; and patients with lissencephaly grades 1 and 2 had hardly any psychomotor development, while those with grades 3 and 4 were severely retarded.