Psych CASC / OSCE · Intellectual disability — neurodevelopmental
Explain fragile X diagnosis and family implications — CASC communication station
MRCPsych/FRANZCP-style communication station: explain FXS without blame, allele classes in plain language, no disease-modifying core cure, supports and comorbidity care, cascade counselling including FXPOI/FXTAS concepts.
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Target exams
Station brief
Format. Communication station, approximately 7–10 minutes active time after reading. You are the dual-diagnosis / CAMHS psychiatry registrar. [1]
Candidate instructions. Explain fragile X syndrome to parents in plain language, cover inheritance and why relatives may need testing, address mother's early menopause carefully, clarify that no medicine cures the gene change, outline school and therapy supports and treatable anxiety/ADHD symptoms, check understanding and offer written information and genetics follow-up. The examiner plays the parents. [1][2]
Candidate scenario
Your patient has molecular confirmation of full-mutation fragile X syndrome. Parents ask: "Did we cause this? Is there a tablet that fixes the gene? Will he get better? Mum's periods stopped early — is that related? Should his sister be tested?" [1][2][3]
Marking domains
- Empathy, structure, agenda-setting; avoid parental blame
- Accurate plain-language explanation of FMR1 full mutation and X-linked inheritance
- Clear statement: no routine disease-modifying core cure; supports + treat comorbidities
- Cascade counselling: mother/sister/maternal-line relatives; FXPOI concept without alarming jargon dump
- School, speech/OT, sensory strategies; anxiety/ADHD as treatable targets
- Checks understanding; offers genetics appointment and written information
- Safety-netting for behavioural crisis and follow-up plan [1][2][4]
Reveal assessor key
Open. Thank them; name the time; ask main worries first. Affirm that seeking help is protective; this is a genetic change, not a failure of parenting love or effort.[1]
Explain FXS. "Fragile X is caused by a change in a gene on the X chromosome called FMR1. In your son's case the gene is 'switched off' because a DNA repeat grew too long (full mutation). That reduces a protein the brain needs for learning and calming sensory input. It can cause learning disability, anxiety, hyperactivity and social difficulties. It is the most common inherited genetic cause of intellectual disability."[1][2]
Inheritance and family. "It is X-linked. Boys with the full mutation are usually more clearly affected. Mothers can carry a smaller 'premutation' change that can expand in a child. That is why we offer genetic counselling and testing for mum and other relatives who may be at risk."[2]
Mother's early menopause. "Some women with a premutation have a higher chance of early menopause or reduced fertility (fragile X-associated primary ovarian insufficiency). Your history is relevant — we will arrange proper genetics and reproductive advice rather than guessing."[3][2]
Medicines. "There is no tablet that turns the gene back on as standard care. If he has ADHD or anxiety that meet treatment thresholds, medicines may help those symptoms with careful monitoring. The main treatment is therapies, school adjustments and a predictable low-stress environment."[1][4]
Hope. Many children make progress with the right supports; we track skills and mental health over time; multiagency plan with education and disability services.[1]
Close. Summarise, invite questions, crisis contacts if aggression or self-injury escalates, written leaflet, genetics appointment, review date with school liaison. [1][2]
References
- [1]Hagerman RJ, Berry-Kravis E, Hazlett HC, et al. Fragile X syndrome Nat Rev Dis Primers, 2017.PMID 28960184
- [2]Hunter JE, Berry-Kravis E, Hipp H, Todd PK FMR1 Disorders GeneReviews, 1993.PMID 20301558
- [3]Allingham-Hawkins DJ, Babul-Hirji R, Chitayat D, et al. Fragile X premutation is a significant risk factor for premature ovarian failure: the International Collaborative POF in Fragile X study Am J Med Genet, 1999.PMID 10208170
- [4]Cordeiro L, Ballinger E, Hagerman R, Hessl D Clinical assessment of DSM-IV anxiety disorders in fragile X syndrome: prevalence and characterization J Neurodev Disord, 2011.PMID 21475730