Spondylometaphyseal dysplasia of the Sedaghatian type is a rare dysplasia, characterized by mild limb shortening, but lethal in the neonatal period. We describe three affected male siblings, the offspring of consanguineous parents. One was stillborn. Neonatal death was due to cardiac arrhythmia in two of the siblings. This report confirms the importance of cardiac pathology in this probably autosomal recessive disorder. This diagnosis should be excluded in any newborn with an arrhythmia as the clinical limb shortening may not be obvious.