Disorder of serine or glycine metabolism 3-phosphoserine phosphatase deficiency ICD10:E72.8 OMIM:614023 3-Phosphoserine phosphatase deficiency is an extremely rare form of serine deficiency syndrome (see this term) characterized clinically by congenital microcephaly and severe psychomotor retardation in the single reported case to date, which was associated with Williams syndrome (see this term). orphanet