From a gene panel
to candidate variants
Investigating familial deafness through targeted sequencing, data analysis and careful interpretation of the evidence.
The research question
The study investigated candidate genetic explanations for hearing loss in two Pakistani brothers. A targeted panel provided a way to examine multiple inherited-disease genes in the same experiment.
This connects with a wider part of my work at RMI: bringing laboratory sequencing, bioinformatic analysis and variant review together for inherited disorders and cancer. The interpretation depends on understanding both the data and the clinical question.
From sequencing to variant review
The team used the TruSight Inherited Disease Panel, covering 552 genes, with Illumina MiSeq sequencing. The published analysis included:
- Read filtering and alignment to hg19/GRCh37.
- Variant calling with GATK HaplotypeCaller.
- Inspection in IGV and annotation review in VariantStudio.
Each stage answers a different question: whether the reads are usable, where they align, which differences are present and how those differences should be evaluated. Keeping these stages connected makes the reasoning behind a candidate finding easier to follow.
What was reported
The paper reported the same MYO7A c.2476G>A variant in both brothers, alongside additional TH and EVC2 variants in the younger brother. For that MYO7A variant, SIFT predicted a deleterious effect, while PolyPhen predicted a benign effect.
A prediction score is one piece of evidence. The useful analytical task is to make agreement, disagreement and missing information visible, so that a candidate can be evaluated in its full context.
The limits of the evidence
Only the two brothers were sequenced. Unaffected relatives were not tested, and the study did not include Sanger confirmation or functional experiments.
These limits leave questions about segregation and biological effect unresolved. The findings are presented here as candidate variants reported in the study, rather than confirmed causes of hearing loss.
What this case illustrates
My role in clinical genomics includes examining sequence evidence, reviewing reference databases and literature, and communicating what a result can support. This case brings those responsibilities into focus: identify potentially relevant variation, document the analysis and keep uncertainty visible.
The same care shapes my approach to pathogen genomics, where a sequence finding also needs to be understood alongside sample quality, analytical support and the question being investigated.
Original publication
Sabiha B, Ali J, Yousafzai YM, Haider SA. Novel deleterious mutation in MYO7A, TH and EVC2 in two Pakistani brothers with familial deafness. Pakistan Journal of Medical Sciences. 2019;35(1):17–22.