Nager syndrome is the prototype for a group of disorders collectively referred to as the acrofacial dysostoses (AFDs), which are characterized by malformation of the craniofacial skeleton and the limbs. The major facial features of Nager syndrome include downslanted palpebral fissures, midface retrusion, and micrognathia, the latter of which often requires the placement of a tracheostomy in early childhood. Limb defects typically involve the anterior (radial) elements of the upper limbs and manifest as small or absent thumbs, triphalangeal thumbs, radial hypoplasia or aplasia, and radioulnar synostosis. Phocomelia of the upper limbs and, occasionally, lower-limb defects have also been reported. The presence of anterior upper-limb defects and the typical lack of lower-limb involvement distinguishes Nager syndrome from Miller syndrome (263750), another rare AFD; however, distinguishing Nager syndrome from other AFDs, including Miller syndrome, can be challenging (summary by Bernier et al., 2012).

The focal dermal dysplasias (FFDDs) are a group of related developmental defects characterized by bitemporal or preauricular skin lesions resembling aplasia cutis congenita. FFFD3 is an autosomal recessive disorder characterized by bitemporal skin lesions with variable facial findings, including thin and puckered periorbital skin, distichiasis and/or absent eyelashes, upslanting palpebral fissures, a flat nasal bridge with a broad nasal tip, large lips, and redundant facial skin (summary by Slavotinek et al., 2013). FFDD2 (614973) is characterized by the same facial features as FFDD3, but the inheritance is autosomal dominant. For a classification and a discussion of genetic heterogeneity of FFDD, see FFDD1 (136500).

A very rare syndrome with the association of thin and short upper and lower tarsus and absence of the lower eyelashes. It has been described in 11 patients from a four-generation family. There is no other unusual feature. Inheritance is autosomal dominant.

RECON progeroid syndrome (RECON) is a chromosomal instability disorder characterized by postnatal growth retardation, progeroid facial appearance, hypoplastic nose, prominent premaxilla, skin photosensitivity and xeroderma, muscle wasting with reduced subcutaneous fat, and slender elongated thumbs (Abu-Libdeh et al., 2022).