[Epileptogenic brain malformations: radiological and clinical presentation and indications for genetic testing]. / Malformations cérébrales et épilepsie: présentations radiocliniques et implications pour le diagnostic génétique.

Malformations of cortical development (MCD) represent a major cause of developmental disabilities and severe epilepsy. Advances in imaging and genetics have improved the diagnosis and classification of these conditions. Up to now, eight genes have been involved in different types of MCD. Lissencephaly-pachygyria and subcortical band heterotopia (SBH) represent a malformative spectrum resulting from mutations of either LIS1 or DCX genes. LIS1 mutations cause a more severe malformation in the posterior brain regions. DCX mutations usually cause anteriorly predominant lissencephaly in males and SBH in female patients. Additional forms are X-linked lissencephaly with corpus callosum agenesis and ambiguous genitalia associated with mutations of the ARX gene. Lissencephaly with cerebellar hypoplasia (LCH) encompass heterogeneous disorders named LCH type a to d. LCHa are related with mutation in LIS1 or DCX, LCHb with mutation of RELN gene, and LCHd could be related with TUBA1A gene. Polymicrogyria encompass a wide range of clinical, aetiological and histological findings. Among several syndromes, recessive bilateral fronto-parietal polymicrogyria has been associated with mutations of the GPR56 gene. Bilateral perisylvian polymicrogyria showed a linkage to chromosome Xq28 in some pedigrees, and mutations in SRPX2 gene in others conditions. X-linked bilateral periventricular nodular heterotopia (BPNH) consists of BPNH with focal epilepsy in females and prenatal lethality in males. Filamin A (FLNA) mutations have been reported in some families and in sporadic patients. It is possible to infer the most likely causative gene by brain imaging studies and other clinical findings. Based on this experience, a detailed phenotype analysis is needed to develop the most efficient research on MCD in the future.

[Diagnostic strategy of beta-thalassemic mutation in a Tunisian family, application in prenatal diagnosis]. / Stratégie diagnostique des mutations beta-thalassémiques dans une famille tunisienne, application au diagnostic prénatal.

At present, the application of combined methods in molecular biology allows us to carry out the prenatal diagnosis in a more rapid and less onerous manner especially when the family presents an index case. In this study, we have analyzed a family with one case of intermediate beta-thalassemia. First, we have used the denaturing gradient gel electrophoresis (DGGE). Then, we have identified the mutations by the refractory mutation system technique (ARMS PCR) using specific primers for the most frequent mutations in the Tunisian population (codon 39 (C --> T) and IVS-I-2 (T--> G) for beta0 thalassemias and IVS-I-110 (G --> A) for beta+ thalassemias). The analyzed family has shown the IVS-I-110 (G --> A) mutation in the heterozygous state in the mother and the index case. Subsequently, sequencing in the gene revealed a frameshift 8 (-AA) mutation in the father and his daughter. This patient is thus a compound heterozygote Codon 8 (-AA)/IVS-I-110. DGGE and ARMS PCR analysis of foetal DNA extracted from trophoblast culture didn't show any of the two mutations found in the family.