Ring 17 syndrome: first clinical report without intellectual disability.

Area of Science:

• Genetics
• Neurology
• Epileptology

Background:

• Ring chromosomes are rare chromosomal abnormalities resulting from telomere fusion.
• Ring chromosome syndromes, including those involving chromosomes 20, 17, and 14, are associated with epilepsy and varied clinical presentations.
• Previous reports suggest epilepsy similarities between ring 17 and ring 20 syndromes, particularly in mild phenotypes.

Purpose of the Study:

• To report the first case of a de novo ring chromosome 17 in a female patient with a normal neurological and cognitive profile.
• To characterize the epilepsy phenotype, including focal pharmacoresistant epilepsy and non-convulsive status epilepticus with autonomic features.
• To investigate potential genetic deletions using array comparative genomic hybridization (array CGH).

Main Methods:

• Cytogenetic analysis to identify the presence and percentage of ring chromosome 17.
• Array CGH with 100 KB resolution to detect chromosomal deletions.
• Clinical and neurological assessment of the patient's cognitive and developmental status.
• Detailed description of the epilepsy characteristics, including seizure types and response to treatment.

Main Results:

• The patient presented with a de novo ring chromosome 17 in 19% of analyzed metaphases.
• No significant genetic deletions were detected by array CGH (100 KB).
• The patient exhibited focal pharmacoresistant epilepsy and non-convulsive status epilepticus with autonomic features, starting at age 9.
• The epilepsy phenotype showed partial resemblance to that observed in ring 20 syndrome.

Conclusions:

• Ring chromosome 17 can occur with a normal neurological and cognitive profile.
• The epilepsy associated with ring chromosome 17 can be severe and pharmacoresistant, presenting with autonomic features.
• The clinical and epilepsy phenotype of ring chromosome 17 may share similarities with ring 20 syndrome, even without detectable deletions via array CGH.