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.
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Reveal interpretationShowHide
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]
References8ShowHide
- [1]Dykens EM Measuring behavioral phenotypes: provocations from the "new genetics" Am J Ment Retard, 1995.PMID 7779347
- [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]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]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]Hagerman RJ, Berry-Kravis E, Hazlett HC, et al. Fragile X syndrome Nat Rev Dis Primers, 2017.PMID 28960184
- [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]Antonarakis SE, Skotko BG, Rafii MS, et al. Down syndrome Nat Rev Dis Primers, 2020.PMID 32029743
- [8]Cassidy SB, Schwartz S, Miller JL, Driscoll DJ Prader-Willi syndrome Genet Med, 2012.PMID 22237428