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PPM - Molecular Genetic Testing of CGG Repeat Expansions in Fragile X Syndrome
Molecular Genetic Testing of CGG Repeat Expansions in Fragile X 
Version: December 2023


This module is an overview of the ACMG technical standards for molecular genetic testing of CGG repeat expansions in the 5’-untranslated region of the FMR1 gene. It is designed to cover Southern blot analysis and/or polymerase chain reaction (PCR) amplification of FMR1 (triplet repeat–primed and methylation specific PCR). However, this module does not address non-CGG repeat expansion variants and AGG interruptions in the FMR1 gene. It is designed for clinical laboratory geneticists who are familiar with FMR1-related disorders and the methods of analysis. Clinical diagnosis, management, and counseling are beyond the scope of this module. Clinical laboratory geneticists are asked to choose 5 male and 5 female cases of fragile X testing that were signed out in your laboratory within the past two years. For each case, answer the following questions regarding the work-up of the cases. Answer choices will be ‘yes’, ‘no’, or ‘not applicable’. At the end of the activity, you will be asked four questions assessing your performance on this module.

Scroll to the bottom of this page for a Preview of the Checklist.


Practice Performance Modules (CCP Part IV)

Practice performance modules are derived from accepted practice guidelines related to genetics patient care. Modules are available for pediatric genetics, adult genetics and prenatal/obstetric genetic care providers.


  1. Educational Content – Review module, literature, and practice checklist
  2. Charting – Each module requires the learner to review 10 patient charts and documenting certain findings according to the module questions.
  3. Assessment and Self-reflection Questions
  4. Evaluation

Completion of these modules should be based on actual patient care as documented in your patient chart
. The process is not meant to be punitive but designed to help assess practice and facilitate practice improvement. The modules should be completed honestly based on documentation in the chart. An audit process may be implemented by ACMG to document compliance. Learners should keep track of the specific charts used to complete the practice module so that these charts could be reproduced in the setting of an audit.

Self-reflections should be meaningful and provide evidence that the diplomate has considered the practice guidelines contained in the exercise in the context of their own clinical practice. Answers to reflection questions should be 2-3 full sentences long and have thoughtful content. Answers to reflection questions will be anonymized and reviewed for content by the MOC committee. Reflections that do not meet these guidelines will be returned to the diplomate for revision. Revisions that do not meet guidelines may result in forfeiture of MOC credit for a given module and a request to repeat the module.

  1. Do you think this module reflects best practice?  Please elaborate whether you agree or disagree and state why.
  2. Did you identify any gaps in your practice?  If so, please elaborate.
  3. If you identified gaps in your practice, what changes do you plan make to your practice based on this module?
  4. What if any barriers do you foresee for implementing change if you identified gaps in your practice? For example, short staffing, time factors etc.