A female presented with progressive loss of vision during night since few months. Fundoscopy shows "bone-spicule formation". Her two brothers and mother are also suffering with the same problem. Diagnosis is:

Retinitis pigmentosa is a group of heterogeneous hereditary retinal degenerations characterized by progressive dysfunction of the photoreceptors, associated with progressive cell loss and eventual atrophy of several retinal layers. Inheritance of the typical form can be autosomal recessive, autosomal dominant, or X-linked recessive. The hallmark symptoms of retinitis pigmentosa are night blindness (nyctalopia) and gradually progressive peripheral visual field loss as a result of increasing and coalescing ring scotomas. The most characteristic fundoscopic findings are attenuated retinal aerioles, waxy pale optic disk, mottling of the retinal pigment epithelium, and 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.