Aase syndrome is caused by a genetic change in genes that help cells build ribosomes, which affects red blood cell production and thumb development before birth.
Ribosomes assemble protein inside every cell, and when the genes that build them are altered, the fastest growing tissues in a developing baby are affected first. That is why the two hallmark features are anemia that shows up in the first months of life and thumbs with three bones instead of the usual two. Most specialists now consider Aase syndrome part of the Diamond-Blackfan anemia spectrum, where changes in ribosomal protein genes such as RPS19 are frequently found. In many families the genetic change is new in the child, so there is no history of it in parents or siblings, and nothing a parent ate, took, or did during pregnancy brings it on. Care works best when a hematologist follows the blood counts and a genetics team looks at the whole picture, including a hand surgeon when thumb function limits daily tasks.
Understanding Aase syndrome
Common questions
What causes Aase syndrome?
Aase syndrome is caused by a genetic change that affects how cells build ribosomes, the structures that make protein. That disrupts early bone marrow and skeletal development, so a baby is born with anemia and with thumbs that have three bones instead of two. Most specialists now group Aase syndrome within the Diamond-Blackfan anemia spectrum, where changes in ribosomal protein genes such as RPS19 are common. Many children have no family history because the genetic change is new in them, and nothing a parent did during pregnancy causes it. A hematologist and a genetics team confirm the picture with blood counts, bone marrow testing, and gene testing.