Mosaic Ring 20 Syndrome: A Meta-Analysis

Area of Science:

• Genetics
• Neurology
• Pediatrics

Background:

• Ring 20 syndrome is a rare childhood neurodevelopmental disorder caused by a structural change in chromosome 20.
• The mosaic form of Ring 20 syndrome is often missed by next-generation sequencing (NGS).
• Karyotype analysis remains the definitive diagnostic test for this condition.

Purpose of the Study:

• To identify distinct clinical characteristics that prompt karyotype testing for Ring 20 syndrome.
• To reduce the diagnostic delay for patients with mosaic Ring 20 syndrome.

Main Methods:

• A systematic literature review was conducted using PubMed and Web of Science.
• Studies reporting on mosaic Ring 20 syndrome were screened and data extracted.
• Data from 70 publications on 148 patients were quantitatively combined.

Main Results:

• Over 90% of cases describe recurrent nonconvulsive status epilepticus.
• Patients typically lack dysmorphic features and develop normally for approximately 7 years before seizure onset.
• Diagnosis should be considered in childhood-onset epilepsy resistant to treatment, especially with normal brain MRI, typical EEG, and negative NGS.

Conclusions:

• Karyotype analysis is the sole definitive diagnostic method for mosaic Ring 20 syndrome.
• Recognizing specific clinical features can shorten the average 7.7-year diagnostic delay.
• Increased awareness among neurologists is essential for timely diagnosis.