is this one extension or two?

Question

As an extension, CRISPR-Cas9 could be utilised on different genes that affect the pathophysiology of thalassemia, such as HBG1/2 and KLF1. Alteration of several different genes could have synergistic effects on foetal haemoglobin levels in thalassemia.

Answer 1

This is one extension. The sentence discusses the potential use of CRISPR-Cas9 on different genes that affect thalassemia, specifically mentioning HBG1/2 and KLF1 genes. This is all part of how CRISPR-Cas9 can be used to potentially increase fetal hemoglobin levels in thalassemia.