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X-linked lissencephaly with abnormal genitalia (XLAG) is a severe neurological disorder that only manifests in genotypic males and includes lissencephaly with posterior-to-anterior gradient and only moderate increase in thickness of the cortex, absent corpus callosum, neonatal-onset severe epilepsy, hypothalamic dysfunction including defective temperature regulation, and ambiguous genitalia with micropenis and cryptorchidism. XLAG differs considerably from classical lissencephaly, as the resulting cortical thickness is only 6-7 mm in XLAG, rather than 15-20 mm seen in classical lissencephaly due to mutations of the PAFAH1B1 or DCX genes. In 2002, mutations in the X-linked aristaless-related homeobox gene (ARX ; Xp21.3) were identified in individuals with XLAG and in some of their female relatives. Mouse Arx and human ARX are highly expressed in both dorsal and ventral telencephalon, including the neocortical ventricular zone and germinal zone of the ganglionic eminence, with less intense signals in the subventricular zone, cortical plate, hippocampus, basal ganglia and ventral thalamus. Arx-deficient mice showed deficient tangential migration and abnormal differentiation of GABAergic interneurons in the ganglionic eminence and neocortex, as well as abnormal testicular differentiation. These characteristics include some of the clinical features of XLAG in humans. The ARX mutations in XLAG patients were predominantly premature termination mutations (large deletions, frameshift, nonsense mutations, splice site mutations) while the missense mutations were less common and located essentially in the homeobox domain. Patients carrying nonconservative missense mutations within the homeobox, showed less severe XLAG, while conservative substitution in the homeodomain caused Proud syndrome (ACC with abnormal genitalia). A non conservative missense mutation near the C-terminal aristaless domain caused unusually severe XLAG with microcephaly and mild cerebellar hypoplasia. The ARX mutations are also associated with a spectrum of milder phenotypes, without macroscopic malformations of the brain, such as X-linked infantile spasms, a syndrome featuring mental retardation associated with distal dystonic movements (Partington syndrome), autistic features and nonsyndromicintellectual deficit.
The Genetic and Rare Diseases Information Center (GARD) has information and resources for patients, caregivers, and families that may be helpful before and after diagnosis of this condition. GARD is a program of the National Center for Advancing Translational Sciences (NCATS), part of the National Institutes of Health (NIH).
View reportOrphanet has a summary about this condition that may include information on the diagnosis, care, and treatment as well as other resources. Some of the information and resources are available in languages other than English. The summary may include medical terms, so we encourage you to share and discuss this information with your doctor. Orphanet is the French National Institute for Health and Medical Research and the Health Programme of the European Union.
View reportOnline Mendelian Inheritance In Man (OMIM) has a summary of published research about this condition and includes references from the medical literature. The summary contains medical and scientific terms, so we encourage you to share and discuss this information with your doctor. OMIM is authored and edited at the McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine.
View reportMedlinePlus has information about this condition that may include a description, frequency, causes, inheritance, and links to more information. The information is written for the public, including patients, caregivers and families. MedlinePlus is a service of the National Library of Medicine (NLM), which is part of the National Institutes of Health (NIH).
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