The Aicardi-Goutières syndrome (familial, early onset encephalopathy with calcifications of the basal ganglia and chronic cerebrospinal fluid lymphocytosis)

Aicardi-Goutières syndrome: clinical and neuroradiological findings of 10 new cases

AIM

To describe the clinical and neuroimaging findings in new cases with Aicardi-Goutières syndrome (AGS) from Egypt.

METHODS

Ten patients with progressive encephalopathy, bilateral calcification of the basal ganglia and spastic quadriplegia were described. Feeding difficulties, irritability, unexplained episodic fever and acrocyanosis were also observed. They were diagnosed as AGS after excluding possible non-genetic causes (especially TORCH) and because of the high interferon-alpha (IFN-alpha) level in cerebrospinal fluid (CSF) in two children who underwent this specific investigation.

RESULTS

Six patients had postnatal microcephaly. Putamen was by far the most common site of calcification (nine cases) inside the basal ganglia. Calcifications were extended to the white matter, periventricular and cerebellum in three cases. Brain atrophy and/or white matter demyelination were evident in most of the cases. Further, hypogenesis of corpus callosum was detected in two cases; one of them had in addition cerebellar hypoplasia, atrial septal defect (ASD) and horseshoe kidney. To the best of our knowledge, the association of these congenital abnormalities has not been reported before in AGS. Eight families were consanguineous.

CONCLUSION

This paper presents variability in both age of onset, clinical picture and neuroimaging findings even in the same family, comprising new congenital abnormalities associated with AGS and subsequently expanding the spectrum of heterogeneity. The observation of familial cases and both affected males and females emphasized the major role of the single gene inheritance.

The genetics of primary dystonias and related disorders

Dystonias are a heterogeneous group of disorders which are known to have a strong inherited basis. This review details recent advances in our understanding of the genetic basis of dystonias, including the primary dystonias, the 'dystonia-plus' syndromes and heredodegenerative disorders. The review focuses particularly on clinical and genetic features and molecular mechanisms. Conditions discussed in detail include idiopathic torsion dystonia (DYT1), focal dystonias (DYT7) and mixed dystonias (DYT6 and DYT13), dopa-responsive dystonia, myoclonus dystonia, rapid-onset dystonia parkinsonism, Fahr disease, Aicardi-Goutieres syndrome, Hallervorden-Spatz syndrome, X-linked dystonia parkinsonism, deafness-dystonia syndrome, mitochondrial dystonias, neuroacanthocytosis and the paroxysmal dystonias/dyskinesias.

Aicardi-Goutieres syndrome in siblings

Two siblings with familial encephalopathy, calcification of the basal ganglia, and cerebrospinal fluid lymphocytosis, constituting the triad of Aicardi-Goutieres syndrome, are reported. This syndrome resembles congenital intrauterine infections, which must be meticulously excluded. Aicardi-Goutieres syndrome is extremely rare and is being reported from the Arab world for the first time to our knowledge.

Aicardi-Goutières syndrome displays genetic heterogeneity with one locus (AGS1) on chromosome 3p21

We have studied 23 children from 13 families with a clinical diagnosis of Aicardi-Goutières syndrome. Affected individuals had developed an early-onset progressive encephalopathy that was characterized by a normal head circumference at birth, basal ganglia calcification, negative viral studies, and abnormalities of cerebrospinal fluid comprising either raised white cell counts and/or raised levels of interferon-alpha. By means of genomewide linkage analysis, a maximum-heterogeneity LOD score of 5.28 was reached at marker D3S3563, with alpha=.48, where alpha is the proportion of families showing linkage. Our data suggest the existence of locus heterogeneity in Aicardi-Goutières syndrome and highlight potential difficulties in the differentiation of this condition from pseudo-TORCH (toxoplasmosis, rubella, cytomegalovirus, and herpes simplex virus types 1 and 2) syndrome.

Aicardi-Goutières syndrome: monogenic recessive disease, genetically heterogeneous disease, or multifactorial disease?

Aicardi-Goutières syndrome (AGS) is a severe progressive familial encephalopathy, which is usually diagnosed shortly after birth. Using the principle of homozygosity mapping, genome-wide screening of five consanguineous families was performed to search for a homozygous region shared by all affected individuals. A total of 364 markers with an average spacing of 9.9 cM were genotyped, but no homozygous region common to all affected individuals could be found. Regions of homozygosity in affected sibs could only be identified within each family individually. This may reflect genetic heterogeneity, possibly related to clinical heterogeneity, since several syndromes are clinically difficult to distinguish from AGS. Involvement of a small number of genes and/or of an external factor, such as infection, may also explain the absence of a homozygous region common to all affected individuals.

Structural and functional neuropathology in transgenic mice with CNS expression of IFN-alpha

Cytokines belonging to the type I interferon (e.g. interferon-alpha) family are important in the host response to infection and may have complex and broad ranging actions in the central nervous system (CNS) that may be beneficial or harmful. To better understand the impact of the CNS expression of the type I interferons (IFN), transgenic mice were developed that produce IFN-alpha(1) chronically from astrocytes. In two independent transgenic lines with moderate and low levels of astrocyte IFN-alpha mRNA expression respectively, a spectrum of transgene dose- and age-dependent structural and functional neurological alterations are induced. Structural changes include neurodegeneration with loss of cholinergic neurons, gliosis, angiopathy with mononuclear cell cuffing, progressive calcification affecting basal ganglia and cerebellum and the up-regulation of a number of IFN-alpha-regulated genes. At a functional level, in vivo and in vitro electrophysiological studies revealed impaired neuronal function and disturbed synaptic plasticity with pronounced hippocampal hyperexcitability. Severe behavioral alterations were also evident in higher expressor GFAP-IFNalpha mice which developed fatal seizures around 13 weeks of age precluding their further behavioral assessment. Modest impairments in discrimination learning were measured in lower expressor GFAP-IFNalpha mice at various ages (7-42 weeks). The behavioral and electrophysiological findings suggest regional changes in hippocampal excitability which may be linked to abnormal calcium metabolism and loss of cholinergic neurons in the GIFN mice. Thus, these transgenic mice provide a novel animal model in which to further evaluate the mechanisms that underlie the diverse actions of type I interferons in the intact CNS and to link specific structural changes with functional impairments.

Aicardi-Goutières syndrome: an update and results of interferon-alpha studies

Twenty-seven patients with familial encephalopathy with calcification of the basal ganglia and chronic cerebrospinal fluid (CSF) lymphocytosis (Aicardi-Goutières syndrome) are reviewed. In 19 children, the onset was within the first 4 months of life. Most patients had normal head circumference at birth, but 21 developed microcephaly between 3 and 12 months. Neuroimaging showed severe and progressive brain atrophy in all patients. The extent and intensity of the calcification was variable even in the same sibship. CSF lymphocytosis persisted beyond 12 months of age in 7 children. High levels of interferon-alpha were found in serum and CSF in 14 patients. The higher CSF levels suggest intrathecal synthesis. Tubuloreticular inclusions related to the presence of interferon were found in 4 additional children. The 19 patients still alive (6 older than 10 years) are profoundly disabled. However, the syndrome may present with individual variations in severity, rapidity of evolution, and imaging features. Neuropathological examination in 2 patients failed to detect significant inflammatory lesions and showed only foci of necrosis and wide-spread demyelination. This study supports an autosomal recessive inheritance for this syndrome. The high level of interferon-alpha is not explained but may play a role in the pathogenesis of the disorder.

Transgenic Expression of IFN-α in the Central Nervous System of Mice Protects Against Lethal Neurotropic Viral Infection but Induces Inflammation and Neurodegeneration

Type I IFNs, which include IFN-α, appear to have complex and broad-ranging actions in the central nervous system (CNS) that may result in protection or injury. To better understand these issues, we generated transgenic mice that produce IFN-α1 chronically from astrocytes. These glial fibrillary acidic protein-IFN-α transgenic mice developed a progressive inflammatory encephalopathy, with marked calcium mineralization, meninoencephalitis, gliosis, and neurodegeneration. Many features of this murine encephalopathy resembled those found in certain human encephalopathies of unknown etiology; these diseases, exemplified by Aicardi-Goutières syndrome and some viral encephalopathies, show increased intrathecal production of IFN-α. Our data suggest that IFN-α overproduction may be the primary factor initiating these human diseases. Following intracerebral infection with lymphocytic choriomeningitis virus, glial fibrillary acidic protein-IFN-α mice had significantly increased survival rates associated with markedly reduced virus titers and immune pathology in the brain but normal peripheral CTL responses. Therefore, the production of IFN-α in the CNS can be a two-edged sword that on the one hand confers protection against a lethal viral infection but on the other causes significant injury to the brain. These transgenic mice provide a novel animal model in which to further evaluate the mechanisms that underlie the diverse actions of type I IFNs in the intact CNS.

Brainstem lesion in Aicardi-Goutières syndrome

Aicardi-Goutières syndrome is characterized by the calcification of basal ganglia, leukodystrophy, and lymphocytosis in cerebrospinal fluid. No brainstem lesion has been described. We report a Japanese girl who presented with delayed development and microcephalus at early infancy. Magnetic resonance imaging revealed T2-weighted high intensity in the cerebral white matter and brainstem, and nerve conduction velocity was delayed in the central nervous system, indicating that she manifested dysmyelination in the brainstem white matter similar to that in the cerebral white matter.

The Aircardi-Goutières syndrome: variable clinical expression in two siblings

We report 2 siblings with the Aicardi-Goutières syndrome (encephalopathy, basal ganglia calcifications, and persistent cerebrospinal fluid pleiocytosis). The eldest sibling is severely retarded; his younger brother has only mild, slowly progressive neurological deficits. To our knowledge, such a striking difference in clinical expression has not been reported previously.