All three children of an unrelated Norwegian couple were born with spinal muscular atrophy (SMA I) as confirmed by autopsy in two of them. Two of the children died at birth, whereas one lived for 7 weeks on support systems that included artificial ventilation. All three children had large atrial septal defects (ASD). One had valvular aortic stenosis. Another had arrhinencephaly and transient pleural effusion which was evacuated during pregnancy. The findings may reflect concurrence of unrelated disorders caused by genetic or environmental factors, segregation of linked genes, pleiotropism or the existence of a previously unknown disease.