Question: What causes Holt-Oram syndrome ?
Answer: What causes Holt-Oram syndrome? Holt-Oram syndrome is caused by changes (mutations) in the TBX5 gene. This gene gives the body instructions for making a protein involved in the development of the heart and upper limbs before birth. In particular, this gene seems important for dividing the developing heart into four chambers, and in regulating the development of bones in the arms and hands. When the TBX5 gene doesn't function properly, the features of Holt-Oram syndrome result. In some cases the mutation occurs for the first time in an affected person, while in other cases the mutation is inherited from a parent. However, in both of these cases, there is nothing a parent can do to cause this mutation or condition in a child.
Source: GARD