[7] In other cases, limitations in computational methods for detecting homologues may result in missed homologous sequences and thus classification of a gene as an orphan.
[11][12] Characteristics of orphan genes include AT richness, relatively recent origins, taxonomic restriction to a single genome, elevated evolution rates, and shorter sequences.
Biologists believe orphan genes may play a crucial role in developing species-specific traits, environmental adaptations, or responses to changing ecological niches.
Similarly, Tautz and Domazet-Loso[17] presented evidence indicating a substantial contribution of orphan genes to phenotypic diversity and adaptation across different species.
Their research underscores the crucial role of orphan genes in driving evolutionary innovation and shaping biological diversity.
"[19] In 2008, a yeast protein of established functionality, BSC4, was found to have evolved de novo from non-coding sequences whose homology was still detectable in sister species.
[31] De novo genes were once thought to be a near impossibility due to the complex and potentially fragile intricacies of creating and maintaining functional polypeptides,[18] but research from the past 10 years or so has found multiple examples of de novo genes, some of which are associated with important biological processes, particularly testes function in animals.
[20][32][33][5][34][35][11][36] For young orphan genes, it is sometimes possible to find homologous non-coding DNA sequences in sister taxa, which is generally accepted as strong evidence of de novo origin.
[45] Of the tens of thousands of enzymes of primary or specialized metabolism that have been characterized to date, none are orphans, or even of restricted lineage; apparently, catalysis requires hundreds of millions of years of evolution.
[46] Orphan genes are theorized to play a critical role in the evolution of species, as they allow organisms to respond to changes in their environment and develop new adaptations rapidly.
For example, some orphan genes are involved in the regulation of growth and development, while others play a role in the response to the environmental stresses.
They argue that genomes contain non-functional open reading frames (ORFs) which might produce spurious polypeptides not maintained by natural selection.
Orphan genes have garnered interest across multiple scientific disciplines such as evolutionary biology and medicine, due to their nature and potential implications.
By clarifying that de novo genes can arise from non-genic sequences and contribute to lineage-specific adaptation, this research expands our understanding of the creative forces of evolution, adding depth and complexity to Darwin's foundational principles.
In medicine, orphan genes represent a rich yet relatively unexplored resource that holds promise for understanding human health and addressing disease.
[52] By elucidating the functions and regulatory mechanisms of orphan genes, researchers can gain insights into various aspects of human health.
Studying these genes can uncover novel disease mechanisms and therapeutic targets, paving the way for the development of innovative treatment strategies.
To name a few, the orphan gene Gpr49, identified in humans, presents itself as a potential novel therapeutic target in combating hepatocellular carcinoma, the predominant form of liver cancer.
Their lineage-specific nature and expression patterns may provide valuable information for personalized medicine approaches, enabling more accurate and targeted interventions for individuals affected by various diseases.
Thus, harnessing the potential of orphan genes in understanding human health has significant implications for advancing biomedical research and improving clinical outcomes.