Baraitser-Winter syndrome (BWS) is a malformation syndrome, characterized by facial dysmorphism (hypertelorism with ptosis, broad bulbous nose, ridged metopic suture, arched eyebrows, progressive coarsening of the face), ocular coloboma, pachygyria and/or band heterotopias with antero-posterior gradient, progressive joint stiffening, and intellectual deficit of variable severity, often with severe epilepsy. Pachygyria - epilepsy - intellectual disability - dysmorphism (Fryns-Aftimos syndrome (FA); see this term) corresponds to the appearance of BWS in elderly patients.

Complete or partial duplication of the phalanges of the thumb. Depending on the severity, the appearance on x-ray can vary from a notched phalanx (the duplicated bone is almost completely fused with the phalanx), a partially fused appearance of the two bones (bifid), two separate bones appearing side to side, or completely duplicated phalanges (proximal and distal phalanx of the thumb and/or 1st metacarpal). In contrast to the phalanges of the digits 2-5 (proximal, middle and distal), the proximal phalanx of the thumb is embryologically equivalent to the middle phalanges of the other digits, whereas the first metacarpal is embryologically of phalangeal origin and as such equivalent to the proximal phalanges of the other digits.