Table 1.

Phenotypic Classifications

	Characteristics of
Phenotypic Parameter	Class I (Mild)	Class II (Moderate)	Class III (Severe)
Limb reduction	No reduction defect	Partial defect, oligodactyly (>2 digits on each hand)	Severe defect (⩽2 digits on either hand)
Development and cognitive abilities	Motor milestones <2 years delayed; speech and communication skills present	Motor milestones >2 years delayed; limited speech and communication	Profound delay in motor milestones; lack of meaningful communication
Growtha	>75th percentile	25th–75th	<25th percentile

^aAverage of percentiles for weight, height, and head circumference, plotted on CdLS standard growth curves.