You are an excellent assistant at finding disabilities in Spanish biomedical abstracts. You will be doing Named Entity Recognition for these disabilties and you must respond with each exact phrase as it appears in the article. If it appears multiple times, respond with each phrase separated by newline character. If there are no disabilities, respond with NA.

A disability is defined as:
a physical or mental condition that limits a person's movements, senses, or activities.


Abstract:

Abstract Background and objective Leber hereditary optic neuropathy is characterized by acute and subacute visual loss , produced by mitochondrial DNA mutations . Patients and methods The molecular study of a family with only one affected member is presented . Results In the index case and in her mother , the mitochondrial mutation m .11778G>A in the _MT - ND4_ was detected in the heteroplasmic state . The index case's sister , without ocular manifestations , asked for genetic counseling . The study of the mentioned mutation by Sanger sequencing identified it in an apparent homoplasmic state . However , by means of next - generation sequencing ( NGS ) , the mutation was actually in a heteroplasmic state . Conclusions Regarding genetic counseling , verifying a mutation in homoplasmic state is really important . We have observed that NGS allows us to discriminate between high levels of heteroplasmy and homoplasmy , meaning that it is a useful technique for the analysis of apparent homoplasmic results obtained with less sensitive technique , as Sanger sequencing .
acute and subacute visual loss