We report a small kindred in which the father and daughter with positive antinuclear antibodies (ANA) (proband) had diffuse cutaneous and visceral scleroderma (systemic sclerosis, SSc), antitopoisomerase autoantibodies and shared the HLA-A23 C- B- DR5 DRw52 DQw3 haplotype. The ANA- granddaughter (daughter of the proband) was noted to have severe isolated pulmonary hypertension within the first 6 months of life, and had the other maternal HLA-A1 Cw8 B14 DR1 DQw1 haplotype, which included a B1, B2 duplication of the C4B allele. All 3 members shared DRw52. The possibility that neonatal pulmonary hypertension represents an isolated autoimmune disease or a hitherto undescribed neonatal syndrome is proposed and the immunogenetic autoantibody implications are discussed.