Inside the cells of a developing human embryo is a little piece of “Alice in Wonderland.” While most of our bodies’ genes are expressed from both our mothers’ and fathers’ chromosomes, there is a particular growth-regulating region of chromosome 11 where Dad’s genes make you grow bigger, and Mom’s genes make you small. As in Alice’s adventure, there is potential for some difficult situations to occur when that growth process is not handled with exacting care.

With new grants awarded by the St. Baldrick’s Foundation and the National Cancer Institute, attending physician and geneticist Jennifer M. Kalish, MD, PhD, at The Children’s Hospital of Philadelphia, is going down the rabbit hole to try to set things right. She aims to answer key questions about cancer while helping children with Beckwith-Wiedemann Syndrome (BWS), an overgrowth disorder that can result when epigenetic regulation of growth-regulating regions of chromosome 11 goes awry.

Five Fascinating Facets of Beckwith-Wiedemann Syndrome

Originally published on Cornerstone, the CHOP Research Blog

I composed this blog post as a complement to the above article about the new investigation into BWS.

Excerpt:

1. BWS is a mosaic condition. Some cells and organs or limbs grow unusually large in children with BWS, and some do not. Patterns of this overgrowth vary from child to child. This mosaicism happens because the changes in gene expression that cause BWS arise early when the developing human embryo has relatively few cells — and the changes occur in only some of them. Cells and organs descended from those dysregulated cells have unusual growth patterns, while cells and organs descended from normally developing cells continue to grow at normal rates. This results in a widely varying presentation of the syndrome in different children.

The mosaic nature of the condition makes it challenging to manage the elevated cancer risk that goes along with BWS. As Dr. Kalish noted, “I can see if a child’s arms are bigger. I cannot see what is going on in the liver or kidney.” Each child’s areas of overgrowth are variable, so all young children with BWS must undergo regular cancer screenings.