Developmental abnormalities of mid and hindbrain: A study of 23 Egyptian patients

Introduction: With the advent of neuroimaging modalities specifically, magnetic resonance imaging (MRI), recognition of developmental defects of posterior fossa has greatly improved. The Aim: Is to delineate the clinical, cytogenetics and radiological features of patients with mid-hindbrain anomalies. Patient and Methods: Twenty-three patients with mid-hind brain malformations were included in this study. Complete clinical evaluation, cytogenetic analysis and neuroradiological study were done for each patient. Patients\' sex ratio was (M: F/ 0.9:1) and the mean age was 2.17 years. Parental consanguinity was 86.9 % and positive family history was recorded in 7 families. Based on clinico-radiological findings, patients were categorized as Joubert syndrome and related cerebellar disorders (34.8%), pontocerebellar hypoplasia (26.1%), lissencephaly cerebellar hypoplasia (13%), isolated cobblestone lissencephaly with normal muscle and eye (8.7%), isolated vermian hypoplasia (13%) and retrocerebellar cyst (4.4%). Results: Cytogenetic analysis revealed abnormalities in 3 patients (13%); pericentric inversion of chromosome 8 in a patient with lissencephaly cerebellar hypoplasia, del 5p14.3-pter delineating Cri du chat syndrome and associated with vermian hypoplasia and del 18q21.1-qter in a patient with retrocerebellar cyst due to paternal balanced translocation t (4;18). FISH for specific locus and whole chromosomal painting were used to document the assigned aberrations. Although most of the cerebellar malformations are of Mendelian inheritance, this study emphasizes the importance of chromosomal analysis for patients with posterior fossa anomalies. With more researches describing clinico-radiological characterization of hind brain dysgenesis will allow better understanding of these disorders, further delineation of relevant syndromes and new genes identification. Keywords: Cerebellar, hindbrain, joubert syndrome, cobblestone lissencephalypontocerebellar hypoplasia, cri du chat syndrome- del 18q21.1-qterEgyptian Journal of Medical Human Genetics Vol. 9 (2) 2008: pp. 215-23