SLC1A4 Deficiency is a severe genetic condition caused by a mutation in the SLC1A4 gene. Approximately 1 in 100 Ashkenazi Jewish people are carriers. People who have SLC1A4 Deficiency have significant cognitive and physical limitations. They are often not able to walk, talk or meaningfully engage with the world. They require lifelong intensive, highly specialized medical care. Life expectancy is also reduced.
SLC1A4 Deficiency typically manifests in infancy or early childhood. Common features include:
MRI typically shows low brain volume, a thin corpus callosumThe bridge of nerve fibers that connects the left and right sides of the brain., and delayed myelinationThe process of coating nerves so brain signals can travel quickly and clearly. leading to significantly impaired brain development during early life.
The gene, the protein, the mutation, and the biochemical mechanism are well characterized. Carrier screening is available and accurate, but is not included on many genetic testing panels.
A natural history study is currently in progress to systematically document the disease course, range of severity, and outcomes for patients with SLC1A4 Deficiency. This study will provide the foundation needed to design future clinical trials and evaluate potential treatments.
Despite growing understanding of SLC1A4 Deficiency, no effective treatments exist. Developing therapies — whether gene therapy, small molecule approaches, or other interventions — requires sustained research investment, animal models, and ultimately clinical trials. Advocacy is needed to add SLC1A4 Deficiency to genetic testing panels. That work can start now with your support.
Approximately 1 in 100 Ashkenazi Jewish people are carriers of SLC1A4 Deficiency. This makes population-based carrier screening critically important; however, SLC1A4 Deficiency is not currently included on most genetic testing panels. Because SLC1A4 Deficiency follows autosomal recessive inheritance, both parents must be carriers for a child to be affected. Each pregnancy of two carriers carries a 25% chance of an affected child. Carrier screening for SLC1A4 is now included in some expanded Ashkenazi Jewish genetic testing panels. OB/GYNs or genetic counselors can provide information about testing.
Couples who are both carriers have options including prenatal diagnosis (CVS or amniocentesis) and preimplantation genetic testing (PGT) with IVF to select unaffected embryos.
People with SLC1A4 Deficiency cannot get protein building-blocks where they need it in the brain. The SLC1A4 gene encodes a protein called ASCT1, an amino acid transporter expressed in astrocytes — the support cells of the brain. ASCT1 is responsible for shuttling the amino acid serine from astrocytes into neurons.
Serine is essential for the synthesis of proteins, membrane lipids, and neurotransmitters. In the developing brain, adequate serine is critical for neuronal growth, myelination, and synaptic function.
SLC1A4 Deficiency is also known as SPATCCM (Spastic Tetraplegia, Thin Corpus Callosum, and Progressive Microcephaly).
The most common pathogenic variant is in the Ashkenazi Jewish population, which is p.Glu256Lys (c.766G>A). It is a founder mutation. When both parents are carriers for this mutation that changes a single amino acid, it disrupts the transporter's function, severely limiting serine supply to neurons during critical developmental windows.