Bartsocas-Papas syndrome 1 (Monarch Disease Ontology entry MONDO_0009901) is a rare, inherited, popliteal pterygium syndrome characterized by severe popliteal webbing, microcephaly, a typical face with short palpebral fissures, ankyloblepharon, hypoplastic nose, filiform bands between the jaws and facial clefts, oligosyndactyly, genital abnormalities, and additional ectodermal anomalies (i.e. absent hair, eyebrows, lashes, nails). It is often fatal in the neonatal period, but patients living until childhood have been reported. Also known as: Bartsocas Papas syndrome, Bartsocas-Papas syndrome, autosomal recessive popliteal pterygium syndrome, lethal popliteal pterygium syndrome, popliteal pterygium syndrome, Bartsocas-Papas type 1, popliteal pterygium syndrome, lethal type.