What is Ring 18: A Sixty-Second Summary

ICD-10 = Q99.9 or Q93.89

Key points on genotype

• Molecular and cytogenetic evaluations are both necessary to make a Ring 18 diagnosis.
• Every patient has unique deletions from BOTH ends of the chromosome; thus Ring 18 is not a single “syndrome.” (For guidance developing an individualized gene-based interpretation see subsequent pages.)
• Some patients have deletions that do not include the deletion of any genes from one of the chromosome arms.
• Therefore, the clinical implication information is separated into 18q (Distal 18q-) and 18p (18p-) in the following pages.
• Some genotype-phenotype correlations have been established and are explored more in the following pages.
• ~20% have duplications just proximal to the breakpoint of up to 30 Mb in size
• Ring 18 occurs in 1 out of 300,000 live births

Key Points on phenotype

• Multiple congenital anomalies are possible. Specific phenotypes are dependent on the specific genes deleted  –  see the section of this report on molecular implications.
• Developmental delay is always present
• Intellectual disability is common but not inevitable
• Failure to thrive and growth hormone deficiency are common
• The risk for autism spectrum is higher than average
• Life expectancy is believed to be near normal except for individuals with very large duplications in addition to the deletions.

Management

• Affected individuals  are not at increased risk for adverse reactions to drugs or standard medical treatments
• Treatment is primarily symptomatic
• Recommendations for specific evaluations  and treatments are in the following sections

Enrollment

• The Chromosome 18 Clinical Research Center is enrolling anyone with any chromosome 18 abnormality in our longitudinal study of all aspects of the conditions.
• Parents need to contact Annice Hill at hilla3@uthscsa.edu or call (210) 567-5321
• We need the diagnostic genetics report and any other informative medical records
• Then we will schedule a blood draw and shipment

Consultation

• Daniel Hale, MD, Medical Director of the Chromosome 18 Clinical Research Center can be reached through Annice Hill at hilla3@uthscsa.edu or call (210) 567-5321.

Updated 2020