We present two siblings (male and female) with very similar characteristics comprising dysmorphic features, severe developmental delay, progressive microcephaly, tonic seizures, and hypothyroidism. The male also had micropenis and cryptorchidism. Both children developed pericardial effusions which caused the death of the female at age 16 months. The male's cardiac function was stable at last follow-up at the age of 15 months. Cerebral imaging showed widespread intracranial calcifications, delay in myelination, hypoplasia of the corpus callosum, and cerebral atrophy. CSF examination showed normal CSF white-cell count and was negative for interferon, although a cytotoxic antibody was thought to be present. Other causes of a neurodegenerative condition and congenital infection were excluded. The combination of these features has not been described before. We believe that these patients represent a new syndrome which has some of the features of Aicardi–Goutières syndrome but is distinct from it.