Mutations in <i>SLC1A4</i>, encoding the brain serine transporter, are associated with developmental delay, microcephaly and hypomyelination

The clinical phenotype of ASCT1 deficiency is reminiscent of defects in L-serine biosynthesis. The data underscore that ASCT1 is essential in brain serine transport. The SLC1A4 p.E256K mutation has a carrier frequency of 0.7% in the Ashkenazi-Jewish population and should be added to the carrier screening panel in this community.