You are seeing a 6 year old boy in your clinic. He has menta…

You are seeing a 6 year old boy in your clinic. He has mental retardation and was also diagnosed with autism. He has a long narrow face and a prominent jaw. His mother tells you that he did not speak until he was 3.5 years old. You talk to his mother, and learn that she is currently experiencing menopause at age 35. She is on medication for anxiety. What is the child’s likely diagnosis?

Two brothers are affected with neurofibromatosis type 1. The…

Two brothers are affected with neurofibromatosis type 1. They inherited a mutation in the NF1 gene from their mildly affected father. One brother has multiple cutaneous neurofibromas, mental retardation and an optic glioma (brain tumor). The other brother has only cafe au lait spots and axillary freckling. The difference in phenotypes between the two brothers is an example of which of the following principles?