Two members of a family presented with loss of vision at night is diagnosed having retinitis pigmentosa. Which of the following is NOT true about retinitis pigmentosa?

Retinitis Pigmentosa: It is a group of heterogeneous hereditary rod-cone dystrophies characterized by progressive dysfunction of the photoreceptors, associated with progressive cell loss and eventual atrophy of retinal layers. It occurs sporadically or in an autosomal recessive, dominant, or X-linked pattern. Hallmark symptoms are night blindness (nyctalopia) and gradually progressive peripheral visual field loss as a result of increasing and coalescing ring scotomas. Most characteristic fundoscopic findings: Attenuated retinal aerioles Waxy pale optic disk Mottling of the retinal pigment epithelium Peripheral retinal pigment clumping, referred to as "bone-spicule formation" Ref: Fletcher E.C., Chong N., Augsburger J.J., Correa Z.M. (2011). Chapter 10. Retina. In P. Riordan-Eva, E.T. Cunningham, Jr. (Eds), Vaughan & Asbury's General Ophthalmology, 18e.