Skip to main content
MMedVellum
MCQsExamsAtlas
DashboardPricing
MMedVellum

The exam atlas that feels like a flagship product — evidence-graded topics and exam tools for MBBS and fellowship preparation. Built to scale to fifty specialties. Educational content only — not medical advice.

llms.txt·psychiatry LLM catalog · sitemap

Atlas

  • Specialty atlas
  • MBBS / Core medicine
  • Dermatology
  • ICU Fellowship (CICM)
  • Anaesthesia
  • Emergency Medicine
  • Psychiatry Fellowship

Study & account

  • MCQ practice
  • Practice alias
  • Exam tools
  • Dashboard
  • Pricing
  • Sign in

© 2026 MedVellum. For education only — not a substitute for clinical judgement.

Clinical Atlas Prestige · Evidence-first

Psych VivasIntellectual disability psychiatry — genetic syndromes

Psych Vivas · Intellectual disability psychiatry — genetic syndromes

Behavioural phenotypes and genetic syndromes — structured clinical viva

Fellowship viva on probabilistic phenotypes, five core syndromes, Boer UPD psychosis, Murphy/Schneider 22q11 evidence, microarray first-tier testing, and start-low go-slow psychopharmacology.

clinical
On this page & tools

Target exams

FRANZCPMRCPsychABPNMD-DNB

Target exams

FRANZCPMRCPsychABPNMD-DNB
Prompt
Examiner: 'Define behavioural phenotype. Compare psychiatric patterns in Down syndrome, fragile X, Prader-Willi, Angelman and 22q11.2DS. A 17-year-old with PWS maternal UPD develops psychosis — what is the evidence link? How do you investigate unexplained ID? How do you prescribe in ID?' Defend mechanisms (imprinting, FMR1, trisomy 21, 22q11), risk numbers teaching points, and pitfalls of diagnostic overshadowing.

Interpretation

Reveal interpretation

Define phenotype. Probabilistic association between syndrome and behavioural/psychiatric patterns (Dykens) — not pathognomonic, not exclusive, not a DSM code.[1]

Five-syndrome comparison. Down (trisomy 21/APP): depression and early Alzheimer risk. Fragile X (FMR1 full mutation greater than 200 CGG): ID, ASD, ADHD, anxiety. PWS (loss of paternal 15q genes): hyperphagia, OCD-like, UPD-linked psychosis. Angelman (maternal UBE3A loss): severe ID, seizures, happy affect, little speech. 22q11.2DS (microdeletion CNV): ADHD/anxiety/ASD traits and high adult psychosis risk.[2][3][4][5][7][8]

PWS UPD psychosis. Boer et al. showed psychotic illness particularly in maternal uniparental disomy PWS — genotype informs risk counselling and vigilance.[4]

22q11 evidence. Murphy: high schizophrenia rates in adult VCFS. Schneider consortium: multi-disorder burden across ages including psychosis risk rising toward adulthood.[2][3]

Investigation. Chromosomal microarray first-tier for unexplained developmental disability/congenital anomalies; add FMR1, 15q methylation, and phenotype-driven tests; involve clinical genetics.[6]

Prescribing. Start low, go slow; treat diagnosed psychosis/depression/ADHD after medical screen; metabolic and cardiac monitoring; food security critical in PWS; avoid diagnostic overshadowing.[3][8]

Key points

Probability not destiny

Phenotype raises priors; you still diagnose the mental disorder present today.[1]

Imprinting pair

Paternal gene loss → PWS; maternal UBE3A loss → Angelman.[8]

22q11 is a psychosis gene model

Highest-tier CNV risk for schizophrenia-spectrum illness — follow into adulthood.[2][3]

References

  1. [1]Dykens EM Measuring behavioral phenotypes: provocations from the "new genetics" Am J Ment Retard, 1995.PMID 7779347
  2. [2]Murphy KC, Jones LA, Owen MJ High rates of schizophrenia in adults with velo-cardio-facial syndrome Arch Gen Psychiatry, 1999.PMID 10530637
  3. [3]Schneider M, Debbané M, Bassett AS, et al. Psychiatric disorders from childhood to adulthood in 22q11.2 deletion syndrome Am J Psychiatry, 2014.PMID 24577245
  4. [4]Boer H, Holland A, Whittington J, et al. Psychotic illness in people with Prader Willi syndrome due to chromosome 15 maternal uniparental disomy Lancet, 2002.PMID 11809260
  5. [5]Hagerman RJ, Berry-Kravis E, Hazlett HC, et al. Fragile X syndrome Nat Rev Dis Primers, 2017.PMID 28960184
  6. [6]Miller DT, Adam MP, Aradhya S, et al. Consensus statement: chromosomal microarray is a first-tier clinical diagnostic test for individuals with developmental disabilities or congenital anomalies Am J Hum Genet, 2010.PMID 20466091
  7. [7]Antonarakis SE, Skotko BG, Rafii MS, et al. Down syndrome Nat Rev Dis Primers, 2020.PMID 32029743
  8. [8]Cassidy SB, Schwartz S, Miller JL, Driscoll DJ Prader-Willi syndrome Genet Med, 2012.PMID 22237428