8q21.11 microdeletion syndrome encompasses heterozygous overlapping microdeletions on chromosome 8q21.11 resulting in intellectual disability, facial dysmorphism comprising a round face, ptosis, short philtrum, Cupid's bow and prominent low-set ears, nasal speech and mild finger and toe anomalies.

The distal interphalangeal joint and/or the proximal interphalangeal joint of the fingers cannot be extended to 180 degrees by either active or passive extension.