Megaloblastic Anemia 1 (AMN)

Megaloblastic anemia 1, also known as Imerslund-Gräsbeck syndrome, is an autosomal recessive disorder caused by pathogenic variants in the gene AMN. While it is diagnosed in individuals worldwide, it has a higher prevalence among individuals of Finnish, Norwegian, and eastern Mediterranean descent. The disease onset is in infancy or early childhood and is characterized by low levels of vitamin B12. Clinical features include megaloblastic anemia, recurrent infections, failure to thrive, fatigue, and proteinuria with normal kidney function. Some individuals also experience mild neurological symptoms, including low muscle tone, delayed development, and numbness or tingling in the extremities. With proper treatment, including vitamin B12 injections, life expectancy is normal. No clear genotype-phenotype correlation has been established.

For information about carrier frequency and residual risk, please see the residual risk table.

This gene is included on the following panel(s):