Sjogren–Larsson Syndrome (SLS) is an autosomal recessive disorder characterized by generalized Ichthyosis, mental retardation, spastic diplegia or tetraplegia and epilepsy. This is a rare syndrome that caused by mutation in the ALDH₃A₂ gene, on chromosome 17p11.2. That encodes fatty aldehyde dehydrogenase (FAIDH), an enzyme that catalyzes the oxidation of medium – long chain aldehydes derived from lipid metabolism.

Neuroimaging (MRI) shows retardation of myelination and a mild myelin deficit. Proton Magnetic Resonance Spectroscopy (MRS) shows the peak of lipids that accumulate because of fatty alchohols. We report two cases that they are siblings from relative parents. The Brother is 4 years old and his sister is 3 years old. , The clinical findings are developmental delay, mental retardation, spastic Tetraplegia and refractory seizure. The most important finding in these two siblings was generalized Icthyosis. MRI showed hyper signality in white matter and MRS showed the peak of accumulated lipids that confirmed the diagnosis of "Sjogren-Larsson Syndrome".