**7. Novel Insights: Macular Telangiectasia**

It has been elucidated recently that a dysregulated lipid metabolism can lead to increased and leaky vasculature [16]. Given the fact that serine homeostasis closely regulates lipid metabolism, it becomes a prime candidate for such monitoring. Interestingly, it was found in patients suffering from Mac Tel that their PHGDH activity is also compromised [85]. This led to severe serine deficiency, which contributed to vascular abnormalities [9]. As explained earlier, serine deficiency further leads to toxic deoxysphingolipid accumulation, which indeed plays a role in the etiology of Mac Tel type 2 [86]. However, administering exogenous serine to patients as a promising therapeutic approach has been marginally successful [87,88]. Importantly, how serine deficiency may affect the RPE and whether that has a role in Mac Tel is not ye<sup>t</sup> known. Nevertheless, it is to be determined whether the restoration of physiological levels of serine in the retina can prevent further neovascularization in Mac Tel patients.
