Targeted gene/disorder under study:

Phelan-McDermid syndrome / deletion 22q13.3 ORPHA:662169


Individuals with a ring chromosome 22 have an increased risk of developing NF2-related tumours. In cells with a ring chromosome mitotic sister chromatid exchanges can lead to interlocked or dicentric ring structures, resulting in loss of the ring chromosome during cell division. As a result, only one copy of the NF2 gene (located at 22q12.2) remains in the cells. In the nervous system, such a cell can develop into a schwannoma or meningioma if a somatic mutation occurs in the remaining NF2 gene. This may result in neurological problems due to the suppression of normal tissue, e.g. deafness due to vestibular schwannomas. 
With this study we would like to answer the following questions. In individuals with a ring chromosome 22:
•    What is the life time risk to develop NF2-related tumours?
•    What is the age range at which the first tumours present and what are the first symptoms?
•    What is the type and localisation of the tumours?
•    Does screening for NF2-related tumours result in early detection and a better outcome?

Coordinating clinician

Carlijn Frantzen, MD, clinical geneticist
Coordinator of the Centre of Expertise for  Phelan-McDermid syndrome 
On behalf of the European Phelan-McDermid syndrome research consortium

Contact email 


University Medical Centre Groningen, Dept. of Genetics, Groningen, Netherlands

Specific requirements beyond clinical data and genotype data sharing:

1- Re-analysis of DNA samples: No

2- Resampling of patients: No

3- Linked to a translational/basic research project: No