Introduction: Hearing loss (HL) represents the most prevalent form of sensory impairment, with an incidence of approximately one to two cases per 1,000 newborns. The prevalence increases with age. In the majority of cases, a genetic etiology is present. The genetic background is heterogeneous, with 156 genes associated with non-syndromic HL and hundreds of genes associated with syndromic HL. Additionally, HL can be associated with pathogenic variants (PVs) in mitochondrial DNA. The experiences and evaluations of patients, families, and parents regarding genetic sequencing in relation to hearing loss are sparsely investigated. Method: The HL characteristics of a large cohort (n=197) of patients with primary mitochondrial disease (PMD) have been retrospectively studied (study I). Prospectively, the genetic variation in patients examined with whole-exome sequencing (WES) (study II) and whole-genome sequencing (WGS) (n=96) (study III) was analyzed. A questionnaire study was conducted to examine parental views on genetic sequencing related to HL as a pilot study (study II). A qualitative interview study, with parents of children with HL examined using WGS, was exploring parental experiences with whole genome sequencing (study IV). Results: Among patients with PMD, more than a quarter (27%) had HL, primarily with onset in schoolage, adolescent, and early adulthood (study I). The overall genetic yield in patients examined with WES/WGS was 43% (studies II, III). In every second patient (48%) with moderate to profound HL, a genetic cause was identified. The diagnostic yield was slightly higher among prelingual cases (52%). Pathogenic variants were identified in 25 different genes, and an autosomal recessive inheritance pattern dominated. PVs associated with isolated HL were identified in 26 cases and syndromic HL in 15 cases. Almost half of the patients (n=43) had parents from another country of birth, primarily from countries in the Middle East (n=29). The diagnostic yield in this group was 58% (n=17/29), and a homozygous autosomal recessive inheritance pattern dominated 82% (n=14/17). In the thematic analysis, three global themes were identified, all of which centered on the concept of knowledge (study IV). The first identified global theme was that limited knowledge, both regarding information and uncertainties within the test result, creates uncertainty. In the second global theme, parents acknowledge the importance of knowledge on both a personal and societal level, as well as its practical implications. Parents identified that knowledge adds complexity and that choices related to knowledge can be challenging as the third global theme. Conclusion: PMD should be considered in cases of postlingual HL. In cases of prelingual moderate to profound HL, a genetic cause could be identified in more than half of the patients, and the genetic background was varied. Additionally, parents found genetic testing to be both personally valuable and practically useful. Thus, considered important for the family and the future.