Paeds Vivas · investigations-procedures-and-technology
Genetic and metabolic test selection — branching viva
Branching viva on the request-side act of choosing and interpreting genetic and metabolic tests: applying the microarray-first consensus, escalating to exome, defending rapid whole-genome sequencing in the NICU, the timing of newborn bloodspot screening, the metabolic window, and the consent for an incidental actionable secondary finding.
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Target exams
RACP DCEMRCPCH ClinicalRCPSC Pediatrics
Prompt
Outpatient clinic: a 4-year-old with global developmental delay and a normal microarray is referred back to you. The examiner asks what you do next, why trio sampling matters, how you would defend rapid whole-genome sequencing in a critically ill neonate, how you explain the timing of a heel-prick, and how you counsel a family for an incidental secondary finding.
Opening question
This 4-year-old with global developmental delay and mild dysmorphism has a normal chromosomal microarray from a year ago. Both parents are available and willing to provide blood. Walk me through your next genetic test of choice, the platform, the sample strategy, and why you would not repeat the microarray or send a karyotype. [1] [2]
References5ShowHide
- [1]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
- [2]Yang Y, Muzny DM, Reid JG, et al Clinical whole-exome sequencing for the diagnosis of mendelian disorders N Engl J Med, 2013.PMID 24088041
- [8]Petrikin JE, Cakici JA, Clark MM, et al The NSIGHT1-randomized controlled trial: rapid whole-genome sequencing for accelerated etiologic diagnosis in critically ill infants NPJ Genom Med, 2018.PMID 29449963
- [11]Miller DT, Lee K, Abul-Husn NS, et al ACMG SF v3.2 list for reporting of secondary findings in clinical exome and genome sequencing: A policy statement of the American College of Medical Genetics and Genomics (ACMG) Genet Med, 2023.PMID 37347242
- [12]Marsden D, Larson C, Levy HL Newborn screening for metabolic disorders J Pediatr, 2006.PMID 16737864