3 ms·

It's an interesting topic. The primary cause of Down syndrome is trisomy of chromosome 21, which is what you described. That form is not inherited. A much less

It's an interesting topic. The primary cause of Down syndrome is trisomy of chromosome 21, which is what you described. That form is not inherited. A much less common cause, mosaicism, is a random occurrence during cell division and isn't inherited either. The only form that can be inherited (that we know of) is caused by translocation. Basically a piece of one chromosome can become switched with a piece of another chromosome. If no information is lost, that's a balanced translocation. Those usually still produce a normal phenotype. When the balanced translocation is passed down a generation, it can lose information or pick up extra information and become unbalanced. If the extra information is from chromosome 21, that can become Down syndrome. That's a simplistic explanation, but should do the job.

im3w1l 3y ago
Right that makes sense. I guess what happens in all of these scenarios is having an extra copy of one particular gene, causes it to become overexpressed, which in turn leads to all these issues?
- thereticent 3y ago
  It's actually many, many genes that are overexpressed and result in the Down syndrome phenotype. My work is with adults with DS and Alzheimer disease--in this case, triplication of the amyloid precursor protein (APP) gene on chromosome 21 nearly guarantees accelerated development of cerebral amyloid deposition compared to typically developing people. But that's just a miniscule part of the Down syndrome phenotype.
thereticent 3y ago
It's actually many, many genes that are overexpressed and result in the Down syndrome phenotype. My work is with adults with DS and Alzheimer disease--in this case, triplication of the amyloid precursor protein (APP) gene on chromosome 21 nearly guarantees accelerated development of cerebral amyloid deposition compared to typically developing people. But that's just a miniscule part of the Down syndrome phenotype.

im3w1l 3y ago

Right that makes sense. I guess what happens in all of these scenarios is having an extra copy of one particular gene, causes it to become overexpressed, which in turn leads to all these issues?

thereticent 3y ago
It's actually many, many genes that are overexpressed and result in the Down syndrome phenotype. My work is with adults with DS and Alzheimer disease--in this case, triplication of the amyloid precursor protein (APP) gene on chromosome 21 nearly guarantees accelerated development of cerebral amyloid deposition compared to typically developing people. But that's just a miniscule part of the Down syndrome phenotype.

thereticent 3y ago

It's actually many, many genes that are overexpressed and result in the Down syndrome phenotype. My work is with adults with DS and Alzheimer disease--in this case, triplication of the amyloid precursor protein (APP) gene on chromosome 21 nearly guarantees accelerated development of cerebral amyloid deposition compared to typically developing people. But that's just a miniscule part of the Down syndrome phenotype.