Some autoimmune diseases show a positive correlation with dramatically decreased expression of histone deacetylase (HDAC9, an enzyme that removes acetyl groups from histones). Why would the decreased expression of HDAC9 cause immune cells to produce inflammatory genes at inappropriate times?

The positive charge of the histone proteins get reduced due to the process of histone acetylation, thus making the wrapping of DNA around the histones less tightened. The loose connected DNA afterward associates with the transcription factors for the articulation of the genes situated in that area.  

Generally, when there is no requirement of gene anymore, the acetyl groups from the histones get withdrawn by the activity of histone deacetylase enzyme (HDAC9) that makes the DNA tightly wrapped and inaccessible again. In case, when less expression of histone deacetylase enzyme occurs, the process of deacetylation fails to take place. This indicates that within an immune cell, at the time of infection, the inflammatory gene, which was made available does not get re-wrapped firmly around the histones.  

starchy vegetables are high in carbohydrates.

starchy vegetables contain more carbohydrates than non-starchy vegetables.

explanation:

there are two primary categories of carbohydrates, essentially differentiated on the basis of their carbohydrate content (which is in the form of starch - a complex carbohydrate):

those vegetables which contain little amounts of starch are termed as non-starchy vegetables, and some examples include: artichokes, broccoli and bean sprouts.

vegetables high in their starch content are distinguished as starchy vegetables, and some examples include: potatoes, chickpeas and corn.