Aicardi syndrome in a 47 XXY male - a variable developmental phenotype?

Fetal Callosal Anomalies: A Narrative Review and Practical Recommendations for Pediatric Neurologists

Agenesis of the corpus callosum is a common indication for fetal neurology consultation, increasingly identified through advances in fetal sonography and fetal magnetic resonance imaging. Despite improvements in diagnostic accuracy, prognostic counseling is challenging due to highly variable neurodevelopmental outcomes. Several factors contribute to neurodevelopmental outcome variability, including associated anomalies and etiologic considerations such as genetic, acquired, and environmental factors. This narrative review discusses existing literature on prenatal findings, postnatal outcomes, and comorbidities to provide practical guidelines for prenatal diagnosis, counseling, and postnatal management. Additionally, practice and research gaps are identified to advocate for guidelines to improve counseling, management, and optimization of outcomes for affected children and families.

Aicardi Syndrome Is a Genetically Heterogeneous Disorder

Aicardi Syndrome (AIC) is a rare neurodevelopmental disorder recognized by the classical triad of agenesis of the corpus callosum, chorioretinal lacunae and infantile epileptic spasms syndrome. The diagnostic criteria of AIC were revised in 2005 to include additional phenotypes that are frequently observed in this patient group. AIC has been traditionally considered as X-linked and male lethal because it almost exclusively affects females. Despite numerous genetic and genomic investigations on AIC, a unifying X-linked cause has not been identified. Here, we performed exome and genome sequencing of 10 females with AIC or suspected AIC based on current criteria. We identified a unique de novo variant, each in different genes: KMT2B, SLF1, SMARCB1, SZT2 and WNT8B, in five of these females. Notably, genomic analyses of coding and non-coding single nucleotide variants, short tandem repeats and structural variation highlighted a distinct lack of X-linked candidate genes. We assessed the likely pathogenicity of our candidate autosomal variants using the TOPflash assay for WNT8B and morpholino knockdown in zebrafish (Danio rerio) embryos for other candidates. We show expression of Wnt8b and Slf1 are restricted to clinically relevant cortical tissues during mouse development. Our findings suggest that AIC is genetically heterogeneous with implicated genes converging on molecular pathways central to cortical development.

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.

Prenatal diagnosis of Aicardi syndrome based on a suggestive imaging pattern: A multicenter case-series

Objectives

To characterize a suggestive prenatal imaging pattern of Aicardi syndrome using ultrasound and MR imaging.

Methods

Based on a retrospective international series of Aicardi syndrome cases from tertiary centers encountered over a 20‐year period (2000–2020), we investigated the frequencies of the imaging features in order to characterize an imaging pattern highly suggestive of the diagnosis.

Results

Among 20 cases included, arachnoid cysts associated with a distortion of the interhemispheric fissure were constantly encountered associated with complete or partial agenesis of the corpus callosum (19/20, 95%). This triad in the presence of other CNS disorganization, such as polymicrogyria (16/17, 94%), heterotopias (15/17, 88%), ventriculomegaly (14/20, 70%), cerebral asymmetry [14/20, 70%]) and less frequently extra‐CNS anomaly (ocular anomalies [7/11, 64%], costal/vertebral segmentation defect [4/20, 20%]) represent a highly suggestive pattern of Aicardi syndrome in a female patient.

Conclusion

Despite absence of genetic test to confirm prenatal diagnosis of AS, this combination of CNS and extra‐CNS fetal findings allows delineation of a characteristic imaging pattern of AS, especially when facing dysgenesis of the corpus callosum.

What is already known about this topic?

Aicardi syndrome (AS) is a rare developmental encephalopathy, characterized by the classic triad of infantile spasms, agenesis of the corpus callosum, and chorioretinal lacunae

As the genetic etiology of AS is unknown and its classic triad cannot be extrapolated to prenatal diagnosis, to establish a prenatal imaging pattern is of major interest

What does this study add?

We confirmed and completed a prenatal imaging pattern highly suggestive of AS, based on the most frequent features encountered in a large series: arachnoid cysts associated with a distortion of the interhemispheric fissure, agenesis of the corpus callosum, cortical malformations and heterotopias, and less frequently extra‐CNS anomaly (ocular anomalies, costal/vertebral segmentation defect)

Aicardi syndrome in a prematurely born baby with retinopathy of prematurity: eye as a window to a systemic pathology

Many of the ophthalmic pathologies can co-exist and when taken together can at times give a clue to a life-threatening systemic condition. Presented here is a case of Aicardi syndrome in a prematurely born baby with retinopathy of prematurity . Early diagnosis by the ophthalmologist helped the baby for a timely neurological attention.

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.

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.