An apparently hitherto undescribed, severe skeletal syndrome is reported in 3 siblings (2 boys, 1 girl) in a family of Turkish-Arabian descent. Major manifestations include: hypoplasia of the pelvis, congenital dislocation of the hip, severe bowing of femora, aplasia or hypoplasia of fibulae, absence or coalescence of tarsal bones, absence of various metatarsals, hypoplasia and aplasia of toes, clinodactyly, hypoplasia of fingers and fingernails, and postaxial polydactyly. Consanguinity is denied, but the fact that both parents belong to the same Christian minority from the same province may indicate common ancestry. Autosomal recessive inheritance is presumed.

Difficulties of differential diagnosis between Prader‐Willi Syndrome and Cohen Syndrome are demonstrated in a 12–year‐old girl with obesity and mental retardation. Cytogenetic studies showed an apparently supernumerary band on chromosome 15 in the proximal region q11‐13. Both parents have a normal karyotype. The aberrant chromosome was derived from an apparently normal paternal chromosome.