Cnr1p1 mRNA is expressed in the cochlea of mice (here 21 days old), as seen on a section going through one cochlear turn, with the blue staining on the left panels corresponding to Cnr1p1, and to the negative control on the right panels. The arrowhead indicates the spiral ganglion neurons which connect hair cells to the brain. The yellow dotted lines indicate the position of hair cells.

In collaboration with human geneticists from Brazil, the Grillet lab revealed the genetic causes of the dominant form of hearing loss DFNA58 as a duplication in Chromosome 2p14 (Lezirovitz et al., 2020, Human Mol. Genetics). The Grillet lab reported the mRNA expression pattern of the three duplicated genes PPP3R1, CNRIP1 and PLEK, each of them is being expressed in the adult mouse cochlea. It will have to be determined which of the three genes is causal to the hearing loss. The main candidate is CNRIP1 (cannabinoid receptor interacting protein 1), which is found upregulated in the blood of patients affected by hearing loss, but not in their unaffected relatives. This work demonstrates that the level of expression of specific genes (or dosage), can lead to hearing loss.

Former members of the Grillet lab, Alix Trouillet (postdoctoral fellow), Ellen Ouyang (Undergraduate student), and Navid Zebarjadi (Research Assistant) here on the picture from left to right, are authors of this work published in Human Molecular Genetics journal.