Intellectual developmental disorder — branching viva

Stem

The examiner starts with definitions, then adds a toddler with multi-domain delay, a school-age child with “learning difficulty,” an acute ED presentation, and an adolescent without transition planning. [1] [5]

Branch 1 — Definition and severity

Examiner: What is intellectual developmental disorder? [5]

Strong answer: A developmental-period condition with significant limitations in intellectual functioning and in adaptive functioning across conceptual, social and practical domains. Severity is based on adaptive support needs, not an IQ number alone. [5]

Examiner: Why not IQ alone? [5]

Strong answer: Intellectual scores and adaptive behaviour are related but not the same construct. Real-world disability requires adaptive impairment. [5]

Branch 2 — Toddler GDD pathway

Examiner: A 2.5-year-old has delayed language, delayed motor skills and limited self-care. No regression. What do you call this and what do you do? [1]

Strong answer: Working label is global developmental delay. I open early intervention now, ensure hearing and vision pathways, take pregnancy/neonatal/family history, examine for dysmorphology and neurology, and start aetiology testing with chromosomal microarray as first-tier genetics, plus fragile X when indicated. I do not wait for school age to help. [1] [2]

Examiner: When would you think metabolic disease? [10]

Strong answer: Regression, episodic decompensation, consanguinity, specific exam or biochemical clues — then prioritise treatable inherited metabolic work-up rather than assuming a static label. [10]

Branch 3 — School-age differential

Examiner: How do you separate IDD from specific learning disorder? [5]

Strong answer: Specific learning disorder is academic skill impairment with intellectual functioning not in the IDD range and without global adaptive disability. IDD requires both intellectual and broad adaptive deficits. [5]

Branch 4 — Acute conversion / overshadowing

Examiner: A child with known moderate IDD presents with new aggression and reduced walking. Staff say “that is his baseline.” Your response? [18]

Strong answer: Baseline explains the past, not a new change. I search for pain, infection, seizure, constipation, dental disease, trauma or abuse. Diagnostic overshadowing is the error to avoid. [18]

Branch 5 — Longitudinal care and transition

Examiner: What does medical-home care look like after diagnosis? [16]

Strong answer: Care coordination across therapy, education and specialty care; preventive surveillance; comorbidity management; family counselling; closed loops on genetics and referrals. [16]

Examiner: When does transition start? [17]

Strong answer: Preparation begins in mid-adolescence inside the medical home — adult providers, emergency plans, decision supports, sexual health and vocational planning — not on the 18th birthday. [17]

Branch 6 — Genomics update

Examiner: After non-diagnostic microarray, what genomic step may be considered? [3]

Strong answer: Exome or genome sequencing is supported by ACMG guidance for pediatric congenital anomalies or intellectual disability as a first- or second-tier test within guideline scope, with counselling about yield and uncertainty. Local access varies. [3]