Congenital anomalies and dysmorphic newborn assessment — branching viva

Stem

You are reviewing a term newborn on the postnatal ward. The baby is hypotonic, with a flat facial profile and bilateral talipes. The parents have noticed that the baby "looks different." The examiner asks you to defend your assessment, your investigation strategy, and your communication. ^[1]

Examiner: Describe the three clinical movements that frame your assessment of a dysmorphic newborn. ^[1]

Strong answer: Recognise the anomaly, cluster the findings into a pattern, and refer for genetics with the right test attached. The first move is always to confirm the baby is stable; only then do I complete the head-to-toe examination, document every major and minor finding, take a three-generation family history, and photograph the features before building a diagnostic ladder. ^[1]

Examiner: The baby has a single palmar crease, a sandal-gap between the toes, and a flat occiput. What is your leading diagnosis? ^[3]

Strong answer: The pattern points to Down syndrome (Trisomy 21). No single feature is diagnostic, but hypotonia with a flat facial profile, upslanting palpebral fissures, a single palmar crease, and sandal-gap toes together form the recognisable gestalt. I would confirm with a karyotype, which is the targeted first-line test when the phenotype points to a whole-chromosome aneuploidy. ^[3]

Examiner: Walk me through your genetic test ladder for a dysmorphic newborn whose pattern does not fit a named syndrome. ^[2]

Strong answer: I start with test pattern points to — karyotype for a clear aneuploidy. When the pattern is unexplained, chromosomal microarray is the first-tier test, because it detects the sub-microscopic copy-number variants a karyotype misses. If the baby is critically ill with a suspected monogenic disorder and the microarray is unrevealing, I escalate to rapid exome or genome sequencing, which shortens time to a molecular diagnosis and can change acute management. ^{[2] [11]}