Polydactyly
Janice L. B. Byrne, MD
DIFFERENTIAL DIAGNOSIS
Common
Familial
Trisomy 13
Diabetic Embryopathy
Less Common
Meckel-Gruber Syndrome
Smith-Lemli-Opitz Syndrome
Carpenter Syndrome
Asphyxiating Thoracic Dysplasia
Rare but Important
Short Rib-Polydactyly
Ellis-van Creveld
Majewski Syndrome
Mohr Syndrome (Oral-Facial-Digital Syndrome)
Bardet-Biedel Syndrome
ESSENTIAL INFORMATION
Key Differential Diagnosis Issues
Clinical history important
Maternal history of diabetes, advanced maternal age (AMA)
Family history of polydactyly
Are there other associated limb anomalies?
Are there other structural anomalies?
Is there evidence of a skeletal dysplasia?
Is there growth restriction (IUGR)?
Where is the extra digit (preaxial vs. postaxial)?
Helpful Clues for Common Diagnoses
Familial
Most commonly postaxial
Increased prevalence in African Americans
Trisomy 13
Multiple anomalies: Orofacial clefts, holoprosencephaly, cardiac, IUGR, AMA
Diabetic Embryopathy
Multiple anomalies: Neural tube defects, holoprosencephaly, anorectal, cardiac
Helpful Clues for Less Common Diagnoses
Meckel-Gruber Syndrome
Classic triad of polydactyly, posterior encephalocele, dysplastic kidneys
Smith-Lemli-Opitz Syndrome
Severe early onset IUGR, cardiac defects, holoprosencephaly, very low estriol
Carpenter Syndrome
Craniosynostosis, complex digital anomalies, cardiac anomalies
Asphyxiating Thoracic Dysplasia
Short horizontal ribs, cystic kidneys, postaxial polydactyly, short extremities
Helpful Clues for Rare Diagnoses
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