Poland Syndrome may have links to other forms of syndactyly, so you maybe able to narrow down some of the patterns, which could include cultural diets or local

Poland Syndrome may have links to other forms of syndactyly, so you maybe able to narrow down some of the patterns, which could include cultural diets or local environmental factors. https://rarediseases.info.nih.gov/diseases/13181/syndactyly https://rarediseases.info.nih.gov/diseases/13181/syndactyly /Edit** This also explains a bit about gene regulation ie switching on & off and ramping them up or down https://www.ncbi.nlm.nih.gov/books/NBK26872/ https://www.ncbi.nlm.nih.gov/books/NBK26872/ /Edit** Clues would be looking at conditions with the same properties like webbing and if its exactly the same condition, treatments for these other conditions may become relevant. There is a lot of studies on Google Scholar and it goes back to the 1800's. Some studies in livestock or vegetation (crops mainly) can also illicit clues because despite being different some chemical reactions or some end results will be the same in humans and animals and plants. You just cant change some of the chemical reactions, melatonin be one that is seen in humans, animals and plants, it increases in darkness.