Question

Why Next-Generation Sequencing (NGS) does not allow to detect expansion repeats disorders (e.g Huntington's disease) and what would a diagram of the coverage of the region for Huntington's disease look like in a coverage plot (e.g Increased/decreased)?

Answer 1

Next generation sequencing (NGS, NextGenSeq) is a new method for sequencing genomes at high speed and at low cost.
It can detect all of those abnormalities using less DNA than required for traditional DNA sequencing approaches. Next-generation sequencing is also less costly and has a faster turnaround time.

Repeat expansions cause more than 30 inherited disorders. whole-exome and whole-genome sequencing (WES and WGS) are used to diagnose genetic disorders.

Next-generation sequencing also requires sophisticated bioinformatics systems, fast data processing and large data storage capabilities, which can be costly.

Next generation sequencing can not distinguish the gene segments from pseudo gene segments. NGS cannot notice the repetitive DNA.
NGS cannot align to reference genome with 100% certainty due to alignment problem.
Because of these limitations, Next-Generation Sequencing (NGS) does not allow to detect expansion repeats disorders (e.g Huntington's disease)