Sribas Chowdhury, Adamas University, Kolkata
Hearing impairment is one of the most common modes of sensory damage in humans and animals. Most hearing impairments are hereditary, i.e., they are inherited from parents before birth. Despite being common, the underlying mechanisms of hereditary deafness are complex and little understood.
The most common cause of hearing loss is Sensorineural Hearing Loss (SNHL). SNHL is associated with autosomal recessive inheritance which results in severe to profound hearing loss. It accounts for more than 90 percent of hearing loss in adults. It is usually nonsyndromic, i.e., it usually doesn’t come with any other signs or symptoms.
Researchers at the University of Helsinki and the Folkhasan Research Center recently identified a variant in a gene named LOXHD1. LOXHD1 is a gene expressed in mechanosensory hair cells in the inner ear. It encodes a highly conservative PLAT (polycystin/lipoxygenase/alpha-toxin) protein which is involved in targeting proteins to the plasma membrane. Defects in this gene have been shown to cause DFNB77, a progressive form of SNHL.
The study, led by Professor Lohi, was centered around a rare type of hereditary impairment seen in Rottweilers, a European breed of dog. The onset happens early in puppies and they eventually become deaf as they turn a few months old. The hearing loss is caused by defects in the gene LOXHD1 and is recessively inherited, i.e., both parents had to have the defect to pass it on to their offspring. Further studies have revealed that newly born dogs who inherit the same defect undergo the same progressive hearing loss. Moreover, the puppies who inherit the defect are either direct descendants of Rottweilers or are a mixed breed of Rottweilers and some other breed.
The study is especially useful for dog breeders who can test dogs before breeding and avoid any chances of birth of a puppy with the gene defect. The researchers have claimed that in addition to dogs, this study can also be beneficial for discoveries in the study of human hereditary impairment and can open new horizons into how we understand genetic defects and their effects on organisms.
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Reference:
- Marjo K. Hytönen, Julia E. Niskanen, Meharji Arumilli, Casey A. Brookhart-Knox, Jonas Donner, Hannes Lohi. Missense variant in LOXHD1 is associated with canine nonsyndromic hearing loss. Human Genetics, 2021; DOI: 10.1007/s00439-021-02286-z
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4441841/
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