Hard-to-align regions

Question. If you scroll around a bit, after a while you'll come across regions where no reads (or very few reads) seem to align. Can you find one? What could cause this?

Hint

If you can't find any, try the ends of chromosomes, or the gene PF3D7_0223500 (which encodes one of the highly polymorphic / duplicated 'var' genes.)

Hint. You could also try searching for the relevant piece of genome sequence using NCBI BLAST. For example, I tried this for one such location:

$ samtools faidx data/reference/Pf3D7_v3.fa.gz Pf3D7_07_v3:343,180-343,380
>Pf3D7_07_v3:343,180-343,380
tatatatatatatatatatatatatatatatatatatataaatatatatatatgtatgta
tgtatgtaatattttagtgcaaaaaaaaaaaaaaaaaaaaaaaaaaagtatataatgaaa
aattattatatatatatatattatatatatatatatatatatatatatatatatatatat
atatatatatatatatatata

and then pasted the above into the Nucleotide BLAST page. (Another version of this can be found on PlasmoDB. Note. you may need to turn off the 'low complexity region' filter to get useful results.