Johanson-Blizzard syndrome was first described in 1971 and now 29 cases have been described world-wide. There is no genetic defect identified and therefore diagnosis remains based on clinical grounds with some assistance from laboratory values. There is a spectrum of clinical features but the hallmarks of the syndrome are hypoplastic alae nasi, dental anomalies, short stature, microcephaly, mental retardation, hypothyroidism, and deafness. Laboratory studies almost uniformly reveal malabsorption and pancreatic examination, through CT imaging or at autopsy, often demonstrate fatty replacement of pancreatic tissue. Pancreatic exocrine malabsorption was once thought a constant feature but there have been reports of normal absorption. This malabsorption is a cause of a failure to thrive in these children. It has been attributed to the short stature and hypothyroidism, and is the usual cause of death. More recently pancreatic endocrine deficiency manifesting as diabetes mellitus has been described. Children have been living longer lives with the advent of pancreatic exocrine enzyme replacement therapy. As the lifespan continues to increase it is postulated more children with this syndrome will begin to develop pancreatic endocrine insufficiency, as modeled by cystic fibrosis where the pancreatic destruction leads to an eventual decline in islet cell mass.
Last update: March 2003