Phenotype and management of Aicardi syndrome: new findings from a survey of 69 children

Diagnostic approach to Aicardi syndrome: A case report

Aicardi syndrome is an X-linked-dominant genetic condition that is present almost exclusively in females. To diagnose Aicardi syndrome, the classic triad of agenesis of the corpus callosum, infantile spasms, and chorioretinal lacunae must be present. Here, we described a case of a female newborn baby delivered at 36 weeks of gestation that arrived at the emergency department with stiffening of arms and legs; therefore, an electroencephalogram was performed, showing generalized polypots confirming infantile spasms. Moreover, magnetic resonance was performed, showing complete agenesis of the corpus callosum. The patient was then transferred for an ophthalmoscopic examination, which evidenced multiple hypopigmented chorioretinal lesions corresponding to chorioretinal lacunae. Based on the clinical and radiological findings, the diagnosis of Aicardi syndrome was established, and treatment with anticonvulsive therapy and physiotherapy was initiated. This case report highlights the main characteristics that clinicians should consider to suspect this rare genetic condition, emphasizing the imaging and electroencephalographic findings.

Aicardi-Goutières syndrome-associated mutation at ADAR1 gene locus activates innate immune response in mouse brain

Background

Aicardi-Goutières syndrome (AGS) is a severe infant or juvenile-onset autoimmune disease characterized by inflammatory encephalopathy with an elevated type 1 interferon-stimulated gene (ISG) expression signature in the brain. Mutations in seven different protein-coding genes, all linked to DNA/RNA metabolism or sensing, have been identified in AGS patients, but none of them has been demonstrated to activate the IFN pathway in the brain of an animal. The molecular mechanism of inflammatory encephalopathy in AGS has not been well defined. Adenosine Deaminase Acting on RNA 1 (ADAR1) is one of the AGS-associated genes. It carries out A-to-I RNA editing that converts adenosine to inosine at double-stranded RNA regions. Whether an AGS-associated mutation in ADAR1 activates the IFN pathway and causes autoimmune pathogenesis in the brain is yet to be determined.

Methods

Mutations in the ADAR1 gene found in AGS patients were introduced into the mouse genome via CRISPR/Cas9 technology. Molecular activities of the specific p.K999N mutation were investigated by measuring the RNA editing levels in brain mRNA substrates of ADAR1 through RNA sequencing analysis. IFN pathway activation in the brain was assessed by measuring ISG expression at the mRNA and protein level through real-time RT-PCR and Luminex assays, respectively. The locations in the brain and neural cell types that express ISGs were determined by RNA in situ hybridization (ISH). Potential AGS-related brain morphologic changes were assessed with immunohistological analysis. Von Kossa and Luxol Fast Blue staining was performed on brain tissue to assess calcification and myelin, respectively.

Results

Mice bearing the ADAR1 p.K999N were viable though smaller than wild type sibs. RNA sequencing analysis of neuron-specific RNA substrates revealed altered RNA editing activities of the mutant ADAR1 protein. Mutant mice exhibited dramatically elevated levels of multiple ISGs within the brain. RNA ISH of brain sections showed selective activation of ISG expression in neurons and microglia in a patchy pattern. ISG-15 mRNA was upregulated in ADAR1 mutant brain neurons whereas CXCL10 mRNA was elevated in adjacent astroglia. No calcification or gliosis was detected in the mutant brain.

Conclusions

We demonstrated that an AGS-associated mutation in ADAR1, specifically the p.K999N mutation, activates the IFN pathway in the mouse brain. The ADAR1 p.K999N mutant mouse replicates aspects of the brain interferonopathy of AGS. Neurons and microglia express different ISGs. Basal ganglia calcification and leukodystrophy seen in AGS patients were not observed in K999N mutant mice, indicating that development of the full clinical phenotype may need an additional stimulus besides AGS mutations. This mutant mouse presents a robust tool for the investigation of AGS and neuroinflammatory diseases including the modeling of potential “second hits” that enable severe phenotypes of clinically variable diseases.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-021-02217-9.

3D facial morphometry in Italian patients affected by Aicardi syndrome

Aicardi syndrome (AIC) is a rare congenital neurodevelopmental disorder of unknown etiology, that affects almost exclusively females, originally characterized by corpus callosum agenesis, chorioretinal lacunae, and infantile spasms. The current diagnostic criteria also include qualitative facial features (prominent premaxilla, upturned nasal tip, decreased nasal bridge angle, sparse lateral eyebrows, and microphthalmia) that still need quantification. A three-dimensional (3D) photogrammetric assessment of 11 Italian females, age 7-32 years, who satisfied AIC criteria, was performed. Linear distances and angles were computed from soft-tissue facial landmarks coordinates. The z-score values were calculated using data of 850 healthy reference females matched for age and compared by Mann-Whitney test (p < .01). Patients showed a shorter philtrum and right side orbital height (mean z-scores: -1.7, -0.9), shorter superior, middle, and inferior facial depths (mean z-scores: -1.3, -2.2, -2.3), and a smaller length of mandibular ramus (mean z-score: -2.1); conversely, they showed larger nasal and lower facial widths, and lower facial convexity (mean z-scores: 1.7, 1.4, 2.4). The inclinations of the orbit versus the true horizontal were increased bilaterally (mean z-scores: 1.8, 1.1). Some common facial abnormalities were quantified in AIC patients using a noninvasive instrument. They may help clinicians in performing a definite AIC diagnosis in atypical or doubt cases.

Corpus Callosotomy for Refractory Epilepsy in Aicardi Syndrome: Case Report and Focused Review of the Literature

BACKGROUND

Aicardi syndrome is a severe neurodevelopmental disorder that occurs primarily in females and is characterized by seizures, agenesis of the corpus callosum, and chorioretinal lacunae, which occur together in the majority of affected individuals. Seizures begin in infancy and tend to progress in intensity and are often refractory to standard multimodal medication treatments.

CASE DESCRIPTION

We present here a unique case of a 12-year-old girl with partial agenesis of the corpus callosum who underwent a corpus callosotomy for treatment of medically refractory epilepsy. In so doing, we also review the literature with regard to the neurosurgical management of these unique patients.

CONCLUSIONS

For the subset of children who present with partial, rather than complete, agenesis of the corpus callosum, corpus callosotomy should be considered as a treatment option to reduce seizure burden.

Precocious and Early Central Puberty in Children With Pre-existing Medical Conditions: A Single Center Study

Background: Precocious and early puberty are reported findings in children with pre-existing medical conditions including certain syndromes. Series pertaining to such situations are limited. Methods: A retrospective, single-center study was conducted on children with central precocious puberty (onset before the age of 8 years in girls and 9 years in boys) or early puberty (onset between 8 and 9 years in girls and between 9 and 10.5 years in boys) diagnosed on the background of a known pre-existing chronic significant medical condition. Patients with a CNS tumor and those exposed to cranial irradiation were excluded. Results: Precocious puberty was diagnosed in 13 patients and early puberty in 12. Mean age at onset of puberty was 6.65 ± 2.3 years in girls (n = 15) and 9.4 ± 0.84 years in boys (n = 10). The most common disorders were psychomotor delay (n = 12), psychiatric disorders (n = 7) and/or epilepsy (n = 5). Precocious or early puberty was among the symptoms experienced by patients with a variety of syndromes including lipofuscinosis (2 siblings), Dravet syndrome and Silver-Russel syndrome. Pituitary stalk interruption with agenesis of olfactory bulbs and optic nerve atrophy was found on imaging in one patient who presented with blindness, epilepsy, and autism spectrum disorder. The other diseases associated with precocious or early puberty are adrenocorticotropic deficiency, dyspraxia and bone abnormalities, glomerulopathy with complete renal failure, and repeated intra-fetal deaths in the mother. Karyotype analysis revealed chromosomal duplication (chromosome 15 in 2 cases; chromosomes 17 and 11 in one case each) in 4 of 8 patients evaluated. Conclusions: Data from patients with complex disease who experience precocious or early puberty may provide clues regarding the genetic determinants of pubertal development.

Aicardi syndrome, an unsolved mystery: Review of diagnostic features, previous attempts, and future opportunities for genetic examination

Aicardi syndrome is a rare, severe neurodevelopmental disorder classically characterized by the triad of infantile spasms, central chorioretinal lacunae, and agenesis of the corpus callosum. Aicardi syndrome only affects females, with the exception of a few males with a 47, XXY chromosome constitution. All cases are de novo and the only cases of definitive recurrence in families are in identical twins. It is now recognized that individuals with Aicardi syndrome commonly exhibit a variety of other neuronal migration defects, eye anomalies, and other somatic features, including skin, skeletal, and craniofacial systems. The etiology of Aicardi syndrome remains unknown despite an international effort exploring different genetic mechanisms. Although various technologies examining candidate genes, copy number variation, skewing of X-chromosome inactivation, and whole-exome sequences have been explored, no strong genetic candidates have been identified to date. New technologies that can detect low-level mosaicism and balanced rearrangements, as well as platforms examining changes at the DNA and chromatin level affecting regulatory regions are all potential avenues for future studies that may one day solve the mystery of the etiology of Aicardi syndrome.

Comorbidities of Rare Epilepsies: Results from the Rare Epilepsy Network

OBJECTIVE

To describe the prevalence and characteristics of comorbidities in persons with rare epilepsies.

STUDY DESIGN

Persons with rare epilepsies and caregivers of those affected were recruited through the Epilepsy Foundation and more than 30 rare epilepsy advocacy organizations affiliated with the Rare Epilepsy Network (REN). A web-based survey was conducted using a questionnaire consisting of core sections to collect data from affected persons on various aspects, including comorbidities. Comorbidity information was grouped into 15 classes, 12 of which had a stem question followed by detailed branch questions and 3 that were created from a combination of related questions.

RESULTS

Of 795 persons with more than 30 different rare epilepsy diagnosis groups, one-half had ≥5 comorbidity classes and 97% were classified as complex chronic disease (C-CD). The highest number of comorbidity classes reported per person were persons with Aicardi syndrome, Phelan-McDermid syndrome (median, 7.0; IQR, 5.0-9.0), and tuberous sclerosis complex (median, 6.0; IQR, 4.0-8.0). The most common comorbidity classes were learning/developmental disability (71%), mental health issues (71%), sleep disorders (60%), brain abnormalities (52%), oral issues (49%), bone-joint issues (42%), hyper/hypotonia (42%), and eye-vision disorders (38%). The prevalence of brain abnormalities, hyper/hypotonia, eye, and cardiac disorders was significantly higher in persons first diagnosed with epilepsy at a younger age (<9 months) than in those first diagnosed at an older age (P < .05 for trend).

CONCLUSIONS

Nearly all persons with rare epilepsies are medically complex, with a high prevalence of multiple comorbidities, especially those who were diagnosed with epilepsy in the first year of life. Comorbidities should be carefully considered in the diagnosis and management of persons with rare epilepsies.

Aicardi syndrome in a 20-year-old female

Purpose

To describe an unusual case of Aicardi Syndrome that both affirms hallmark characteristics of the condition and introduces new observations.

Observations

We report the case of a 20-year-old woman with Aicardi Syndrome who presented in respiratory distress with bradycardia and died soon thereafter. She had a history of severe mental retardation, seizure disorder, advanced scoliosis and numerous contractures in addition to congenital ocular malformations resulting in bilateral blindness. The case is notable for her age and longevity, as most patients with Aicardi Syndrome expire much younger, as well as the presence of intact nuclei under the posterior lens capsule.

Conclusions and importance

Aicardi Syndrome is a rare X-linked cerebro-retinal disorder typified by seizures, agenesis of the corpus callosum, and chorioretinal lacunae. Documenting alterations from and additions to this triad of symptoms is critical to better understanding both the syndrome itself, as well as the full breadth of its clinical impact on the patient.

Independent variant analysis of TEAD1 and OCEL1 in 38 Aicardi syndrome patients

Background

Aicardi syndrome is a severe neurodevelopmental disorder characterized by infantile spasms, typical chorioretinal lacunae, agenesis of the corpus callosum, and other neuronal migration defects. It has been reported recently that de novo variants in TEAD1 and OCEL1 each may cause Aicardi syndrome in a single individual of a small cohort of females with this clinical diagnosis. These data were interpreted to suggest that the clinical diagnosis of Aicardi syndrome may be genetically heterogeneous.

Methods

To investigate this further, we sequenced TEAD1 and OCEL1 coding regions using DNA from 38 clinically well‐characterized girls with Aicardi syndrome.

Results

We did not detect the previously reported or any other deleterious variants in any of the analyzed samples.

Conclusions

This suggests that the published variants represent either an extremely rare cause of Aicardi syndrome or an incidental finding.

Scoliosis in Children With Aicardi Syndrome

BACKGROUND

Aicardi syndrome (ACS) is a rare neurodevelopmental disorder that was classically characterized by the triad of agenesis of corpus callosum, infantile spasms, and chorioretinal lacunae. As new cases emerge and new common phenotypic features are being described in subsequent reports, new modified diagnostic criteria have been proposed that now classify the observed costovertebral abnormalities as supporting diagnostic features. To our knowledge there are no previous studies focusing and describing the scoliosis observed in children with ACS.

METHODS

We screened billing lists to identify patients seen in the Division of Orthopaedic Surgery at our institution with a diagnosis of ACS that were treated for scoliosis after 2001. A total of 5 patients were identified. Medical records and radiographs were retrospectively reviewed in all cases. In all of the patients the diagnosis of ACS had been confirmed through complete genetic evaluation and advanced imaging.

RESULTS

The mean age when scoliosis was first noticed was 3.9±4.2 years (range, 0.5 to 10.5 y) with a mean Cobb angle of 22.5±6.7 degrees (range, 10 to 27 degrees). The mean age at the first orthopedic visit was 5.8±5.0 years (range, 1.5 to 13 y) with a progressed mean Cobb angle of 39.5±17.3 degrees (range, 15 to 57 degrees). Congenital vertebral anomalies were observed in 1 patient. Three patients were treated surgically; 1 of the 3 patients had a surgical complication with loss of intraoperative neuromonitoring signals. Two patients had not undergone surgery at the last visit with a mean Cobb angle of 75.5 degrees. The mean postoperative follow-up for the surgical group (cases 1 to 3) was 3±3.6 years (range, 0.6 to 7.2 y) and the mean total follow-up for both groups was 6.6±2.5 years (range, 2.6 to 8.6 y).

CONCLUSIONS

Scoliosis in ACS can represent a clinically significant problem that is underdiagnosed and overshadowed by the other severe medical complications associated with the syndrome. Our data suggest that scoliosis in patients with ACS is rapidly progressive and bracing is ineffective; early screening, close observation, and low threshold for referral to an orthopedic surgeon are crucial.

LEVEL OF EVIDENCE

Level IV-case series.

Aicardi syndrome: an epidemiologic and clinical study in Norway

BACKGROUND

Aicardi syndrome is a rare neurodevelopmental disorder. The main diagnostic features are agenesis of corpus callosum, chorioretinal lacunae, and infantile spasms. The outcome is in general severe, with poor cognitive development and difficult-to-treat epilepsy. The aim of this study was to perform a nationwide epidemiologic survey of patients with Aicardi syndrome and describe their clinical features. Norway is a small country with a well-developed health system, making epidemiologic studies of rare diseases feasible and reliable.

METHODS

We aimed at identifying all patients diagnosed with Aicardi syndrome in Norway. Prevalence of Aicardi syndrome was calculated for January 1, 2011. All available patients were examined, and their medical records were scrutinized.

RESULTS

Six females aged 7 to 27 years with the diagnosis of Aicardi syndrome were identified. With a female population of 949,578 in ages 0 to 29 years, we found an age-adjusted prevalence of 0.63 per 100,000 females. One patient never had epileptic seizures. The other five had all experienced infantile spasms, all had at some point hypsarrhythmia in electroencephalography, two had a clear picture of suppression burst, whereas three had periods of suppression. Four of the five patients with seizure disorders experienced a marked improvement with time.

CONCLUSION

We found an age-adjusted prevalence of 0.63 per 100,000 females with Aicardi syndrome and that their seizure disorder appeared to improve with age.

Palliative epilepsy surgery in Aicardi syndrome: a case series and review of literature

PURPOSE

Aicardi syndrome (AS) is a severe neurodevelopmental disorder characterized by the triad of seizures, agenesis of corpus callosum, and chorioretinal lacunae. Seizures in AS are typically frequent, of various types, and refractory to medical therapy. Optimal treatment of seizures in AS remains undetermined.

METHODS

We report a series of four patients with Aicardi syndrome who underwent surgical management of their epilepsy including two with corpus callosotomy (CC) of a partial corpus callosum and three with vagus nerve stimulator implantation.

RESULTS

Seizure outcome was variable and ranged from near complete resolution of seizures to worsening of seizure profile. The most favorable seizure outcome was seen in a patient with partial agenesis of the corpus callosum treated with CC.

CONCLUSIONS

Seizure outcome following CC or vagus nerve stimulation in patients with Aicardi syndrome is variable. Although palliative epilepsy surgery may result in improvement in the seizure profile in some patients, studies on larger patient cohorts are needed to identify the precise role that surgery may play in the multidisciplinary approach to controlling seizures in Aicardi syndrome.

Aicardi syndrome associated with autosomal genomic imbalance: coincidence or evidence for autosomal inheritance with sex-limited expression?

Aicardi syndrome (AIS), a rare neurodevelopmental disorder thought to be caused by an X-linked dominant mutation, is characterized by 3 main features: agenesis of corpus callosum, infantile spams and chorioretinal lacunae. A genome-wide study of a girl with AIS lead us to identify a 6q deletion;12q duplication, derived from a maternal 6q;12q translocation. The two intellectually impaired brothers of the proband showed the same genomic anomalies, but not the constellation of features characterizing the AIS. This could be either a coincidental observation of 2 rare conditions, but can also suggest an alternative hypothesis for the genetic etiology of AIS, indicating the existence of a subset of autosomal genes whose mutation could act in a sex-confined manner.

Using a parent survey to advance knowledge about the nature and consequences of fragile X syndrome

Understanding the nature and consequences of intellectual and developmental disabilities is challenging, especially when the condition is rare, affected individuals are geographically dispersed, and/or resource constraints limit large-scale studies involving direct assessment. Surveys provide an alternative methodology for gathering information but must be carefully designed and interpreted in light of obvious limitations. In this paper we discuss the potential of surveys in understanding a disabling condition; delineate characteristics of successful survey research; describe a survey of families of individuals with fragile X syndrome; and synthesize major findings. The survey has provided new information about the nature and consequences of fragile X syndrome in a cost-effective fashion, suggesting that survey methodology has a useful place in creating new knowledge about intellectual and developmental disabilities.

A genome-wide screen for copy number alterations in Aicardi syndrome

Aicardi syndrome is a severe neurodevelopmental disorder that affects females or rarely males with a 47,XXY karyotype. Therefore, it is thought to be caused by heterozygous defects in an essential X-linked gene or by defects in an autosomal gene with sex-limited expression. Because all reported cases are sporadic with one exception, traditional linkage analysis to identify the mutant gene is not possible, and the de novo mutation rate must be high. As an alternative approach to localize the mutant gene, we screened the DNA of 38 girls with Aicardi syndrome by high-resolution, genome-wide array comparative genomic hybridization for copy number gains and losses. We found 110 copy number variants (CNVs), 97 of which are known, presumably polymorphic, CNVs; 8 have been seen before in unrelated studies in unaffected individuals. Four previously unseen CNVs on autosomes were each inherited from a healthy parent. One subject with Aicardi syndrome had a de novo loss of X-linked copy number in a region without known genes. Detailed analysis of this and flanking regions did not reveal CNVs or mutations in annotated genes in other affected subjects. We conclude that, in this study population of 38 subjects, Aicardi syndrome is not caused by CNVs detectable with the high-resolution array platform that was used.

Non-random X chromosome inactivation in Aicardi syndrome

Most females have random X-chromosome inactivation (XCI), defined as an equal likelihood for inactivation of the maternally- or paternally-derived X chromosome in each cell. Several X-linked disorders have been associated with a higher prevalence of non-random XCI patterns, but previous studies on XCI patterns in Aicardi syndrome were limited by small numbers and older methodologies, and have yielded conflicting results. We studied XCI patterns in DNA extracted from peripheral blood leukocytes of 35 girls with typical Aicardi syndrome (AIC) from 0.25 to 16.42 years of age, using the human androgen receptor assay. Data on 33 informative samples showed non-random XCI in 11 (33%), defined as a >80:20% skewed ratio of one versus the other X chromosome being active. In six (18%) of these, there was a >95:5% extremely skewed ratio of one versus the other X chromosome being active. XCI patterns on maternal samples were not excessively skewed. The prevalence of non-random XCI in Aicardi syndrome is significantly different from that in the general population (p < 0.0001) and provides additional support for the hypothesis that Aicardi syndrome is an X-linked disorder. We also investigated the correlation between X-inactivation patterns and clinical severity and found that non-random XCI is associated with a high neurological composite severity score. Conversely, a statistically significant association was found between random XCI and the skeletal composite score. Correlations between X-inactivation patterns and individual features were made and we found a significant association between vertebral anomalies and random XCI.

A male phenotype with Aicardi syndrome

Aicardi syndrome is a rare neurodevelopmental condition that occurs almost exclusively in women. We report a second male phenotype and 47,XXY karyotype with a typical presentation of the Aicardi syndrome including a midline arachnoid cyst.

Cerebellar migration defects in aicardi syndrome: an extension of the neuropathological spectrum

The Aicardi syndrome is characterized by infantile spasms, corpus callosum agenesis, and chorioretinal lacunae and almost exclusively affects females (very rarely, 47, XXY males). The crucial genetic mishap likely occurs in the postzygotic stage, but the variable clinical phenotype among the approximately 450 known cases has not been explained. No consistent mutations or deletions exist among patients. We encountered a baby girl with early onset infantile spasms. She had left-sided cleft lip/palate, costovertebral defects, scoliosis, callosal agenesis, and microphthalmia. She expired at the age of 3 months of respiratory infection. On autopsy she had thoracic hemivertebrae with rib defects, bilateral microphthalmia, microcornea, posterior colobomata, abnormalities of the retinal pigment epithelium, absence of normal ganglion cells in the retina, gross asymmetry of the brain with cerebral polymicrogyria, total callosal agenesis, cerebral subcortical and subependymal nodular heterotopias, cerebellar nodular heterotopias, and tegmental/basal unilateral brainstem hypoplasia. Cerebellar and retinal migration defects have not been described before in Aicardi syndrome and may have had a bearing on this patient's eventual outcome.

Aicardi syndrome in a genotypic male

Aicardi syndrome was originally described as a triad of partial or complete agenesis of the corpus callosum, infantile spasms, and pathognomic chorioretinal lacunae. Of approximately 200 cases reported since it was originally described in 1965, there have been no undisputed reports of Aicardi syndrome in a 46 XY male. Thus a dominant X-linked inheritance, presumed lethal in males, has been proposed. Herein we report a 5 year-old 46 XY male with the classic clinical triad of Aicardi syndrome.

New incidence, prevalence, and survival of Aicardi syndrome from 408 cases

We sought to determine the incidence, prevalence, and life expectancy of Aicardi syndrome from 408 cases compiled from multiple international sources. Last known age ranged from less than 1 month to 42 years. The incidence rates per live births for the United States and The Netherlands were 1 per 105 000 and 1 per 93 000, respectively. The prevalence in the United States is greater than 853 cases, and the worldwide estimate is several thousand. Forty-five cases were deceased (age range, 1 month to 33 years), and the risk of death peaked at age 16. The probability of survival at 27 years of age was 0.62 (95% CI, 0.47-0.77). The risk of death by age follows other congenital neurological disorders with a wide range in severity of functional disability. The longer life expectancy found in our study hints at a higher functioning capacity in Aicardi syndrome and may inform counseling to families.