WHAT IS Sesame/East Syndrome?

By: Maria Smietana

EAST (Epilepsy, Ataxia, Sensorineural hearing loss, and Tubulopathy) syndrome, also known as SeSAME (Seizures, Sensorineural deafness, Ataxia, intellectual (Mental) disability, and Electrolyte imbalance) syndrome, is an inherited condition. Caused by one or more mutations in a gene known as KCNJ10, EAST/ SeSAME syndrome is an autosomal recessive trait. Autosomal simply means that the gene is found on one of the 22 numbered human chromosomes, as opposed to the X or Y chromosome. Recessive traits are those that are only passed on when BOTH parents carry the mutated (non-functional) gene. This mutation is so rare that the likelihood of two carriers finding each other and having children is almost nonexistent – the chance of having a child with EAST/SeSAME syndrome is less than one in one million. A medical review published in 2019 stated that less than three dozen children across the world had been diagnosed with this syndrome since it was first described by researchers in 2009.

The KCNJ10 gene is responsible for the way potassium moves into cells, especially in the brain, ear, eye and kidney, a process that is critical to the normal functioning of those organs. When potassium channels don’t function properly, it sets off a domino effect that ultimately results in the group of symptoms that make up EAST/SeSAME syndrome.

Which aspect of the syndrome appears first varies from patient to patient, but because we are a highly vocal species, parents tend to notice quickly if their newborn does not respond to sound. Ataxia presents itself as a baby who feels weak or “floppy.” Ataxia is a broad term that describes poor muscle control, impaired balance and coordination, lack of fine motor control, difficulty eating and swallowing, abnormal gait, and abnormal eye movement. A little later, ataxia becomes obvious as the child struggles to grasp and hold objects and shows delays in crawling, walking, and talking. Seizures, which usually occur between 3 and 9 months, are the tonic-clonic (grand mal) type, also seen in many other conditions. Tubulopathy describes an abnormality of the tubules inside the kidney. We primarily think of the kidneys as the organs that remove waste products from our bodies, which we excrete in our urine. But the tubules are also critical in regulating the flow of minerals, such as potassium, sodium, and calcium, necessary for our cells to function. Most EAST/SeSAME patients also exhibit delays or impairment in intellectual development, especially if their ataxia substantially interferes with speech, but with appropriate support, many function only slightly behind their peer group.

While there is no cure for EAST/SeSAME syndrome, all its component conditions respond to treatment, especially if intervention starts early. Hearing aids and cochlear implants restore lost hearing and help with speech development. Various anticonvulsants are available to treat seizures, and mineral supplements help potassium, sodium, calcium, and other electrolytes to stay in balance. Therapies, including physical, occupational, and speech, are employed to help develop motor skills and communication and facilitate learning.