is the most severe form of a spectrum of conditions called Zellweger spectrum. The signs and symptoms of Zellweger syndrome typically appear during the newborn period and may include poor muscle tone (hypotonia), poor feeding, seizures, hearing loss, vision loss, distinctive facial features, and skeletal abnormalities. Affected children also develop life-threatening problems in other organs and tissues, such as the liver, heart, and kidneys. Children with Zellweger syndrome usually do not survive beyond the first year of life. Zellweger syndrome is caused by mutations in any one of at least 12 genes; mutations in the PEX1 gene are the most common cause. It is inherited in an autosomal recessive manner. There is no cure for Zellweger syndrome; treatment is generally symptomatic and supportive. Source: Genetic and Rare Diseases Information Center (GARD), supported by ORDR-NCATS and NHGRI.