FMR protein: Evidence of an emerging role in retinal aging?

Aging is a multifactorial process that affects the entire organism by cumulative alterations. Visual function impairments that go along with aging are commonly observed, causing lower visual acuity, lower contrast sensitivity, and impaired dark adaptation. Electroretinogram analysis revealed that the amplitudes of rod- and cone-mediated responses are reduced in aged mice and humans. Reports suggested that age-related changes observed in both rod and cone photoreceptor functionality were linked to oxidative stress regulation or free radical production homeostasis. Interestingly, several recent reports linked the fragile X mental retardation protein (FMRP) cellular activity with oxidative stress regulation in several tissue including brain tissue where FMRP participates to the response to stress via protein translation in neurite or is involved in free radical production and abnormal glutathione homeostasis. Based on these recent literatures, we raised the question about the effect of FMRP absence in the aging retina of Fmr1^-/y compared to their WT littermates. Indeed, up to now, only young or adult mice (<6 months) were investigated and have shown a specific retinal phenotype. Herein, we demonstrated that Fmr1^-/y mice do not present the aging effect on retinal function observed in WT littermates since ERG a- and b-waves amplitudes as well as oscillatory potentials amplitudes were not collapsed with age (12/18 months old). Absence of FMRP and its consequences seem to protect the retina against aging effect, rising a pivotal role of FMRP in retinal aging process.

[Cellular neurothekoma in an 11-year-old child]

INTRODUCTION

Neurothekoma is a rare benign tumor which must be distinguished from certain malignant tumors such as fibrohistiocyte tumors or plexiform cell tumors, neurotropic melanomas and clear-cell sarcoma.

CASE REPORT

An 11-year-old girl consulted for a recurrent subcutaneous tumor of the chin which had been operated 4 months earlier. The resection was incomplete. A wider revision resection successfully stopped recurrence. The histology study established the diagnosis of neurothekoma due to the presence of mitosis atypia, cellular nodules, and extension to the hypodermis. Immunohistochemistry confirmed the diagnosis.

DISCUSSION

Neurothekoma is a benign tumor observed in young women, mainly on the face. It occurs as a dermal cohesive mass without infiltration of the epidermis. The typical immunohistochemical pattern enables differential diagnosis with myxoid neurothekoma, melanocytic and nervous system tumors. Surgical resection is indicated.