Deborah Marsden, MD, Global Medical Expert, Medical Affairs, Ultragenyx, discusses the potential connection between mucopolysaccharidosis type VII (MPS VII) survival and non-immune hydrops fetalis (NIHF).

MPS VII, or Sly syndrome, is a rare progressive metabolic condition that affects most tissues and organs. The severity of MPS VII varies widely among affected individuals. Individuals with MPS VII often begin to display symptoms of the condition during early childhood which may include: macrocephaly, hydrocephalus, macroglossia, hepatosplenomegaly, heart valve abnormalities, and umbilical or inguinal hernias. The life expectancy of individuals with MPS VII depends on the severity of symptoms. Some affected individuals do not survive infancy, while others may live into adolescence or adulthood. Heart disease and airway obstruction are major causes of death in people with MPS VII. 

NIHF is a severe fetal condition characterized by the excessive accumulation of fetal fluid within the fetal extravascular compartments and body cavities. As Dr. Marsden explains, in a program including 37 MPS VII patients from around the world, 68% had NIHF. Unfortunately, NIHF not only often leads to fetal demise but it can also lead to being born prematurely, which creates further health risks. The team leading this program found that those with NIHF who were treated had a 51% mortality rate in the first year of life while those patients with MPS VII but not NIHF had a 100% one-year survival rate. 

To learn more about MPS VII and other rare metabolic disorders, visit