In humans, SEC23A missense mutations result in cranio-lenticulo-sutural-dysplasia (CLSD), an autosomal recessive disease characterized by skeletal abnormalities, late closure of fontanelles, dysmorphic features, and sutural cataracts17, while multiple loss of function SEC23B mutations have been identified in patients with congenital dyserythropoietic anemia type II (CDAII)18. Here, SEC23B is linked to Congenital dyserythropoietic anemia type II.