Any retinitis pigmentosa in which the cause of the disease is a mutation in the NRL gene.

Retinitis pigmentosa (RP) is a clinically and genetically heterogeneous group of retinal dystrophies characterized by a progressive degeneration of photoreceptors, eventually resulting in severe visual impairment. For a discussion of genetic heterogeneity of RP, see 268000.

An autosomal recessive retinopathy in which patients have increased sensitivity to blue light; perception of blue light is mediated by what is normally the least populous cone photoreceptor subtype, the S (short wavelength, blue) cones. Characteristics include visual loss, with night blindness occurring from early in life, varying degrees of L (long, red)- and M (middle, green)-cone vision, and retinal degeneration.

Retinal vasculopathy with cerebral leukoencephalopathy and systemic manifestations (RVCL-S) is a small-vessel disease that affects highly vascularized tissues including the retina, brain, liver, and kidneys. Age of onset is often between 35 and 50 years. The most common presenting finding is decreased visual acuity and/or visual field defects. Neurologic manifestations may include hemiparesis, facial weakness, aphasia, and hemianopsia. Migraines and seizures are less frequently described. Renal manifestations may include mild-to-moderate increase in serum creatinine and mild proteinuria; progression to end-stage renal disease (ESRD) is uncommon. Hepatic manifestations frequently include mildly elevated levels of alkaline phosphatase and gamma-glutamyltransferase (GGT). Less common findings include psychiatric disorders, hypertension, mild-to-moderate anemia, and Raynaud phenomenon.

Autosomal dominant retinitis pigmentosa (ADRP) is characterized by a typical fundus appearance, narrowed retinal vessels, and changes in the electrophysiological responses of the eye. Early signs are night blindness and constriction of the visual fields with a variable ages of onset (summary by Jay et al., 1992).

TRNT1 deficiency encompasses what was first thought to be two separate disorders, a severe disorder called sideroblastic anemia with B-cell immunodeficiency, periodic fevers, and developmental delay (SIFD) and a milder disorder called retinitis pigmentosa with erythrocytic microcytosis (RPEM), each named for its most common features. SIFD begins in infancy, and affected individuals usually do not survive past childhood. RPEM, on the other hand, is recognized in early adulthood, and the microcytosis usually does not cause any health problems. However, it has since been recognized that some individuals have a combination of features that fall between these two ends of the severity spectrum. All of these cases are now considered part of TRNT1 deficiency.\n\nIn addition, many individuals with TRNT1 deficiency have recurrent fevers that are not caused by an infection. These fever episodes are often one of the earliest recognized symptoms of TRNT1 deficiency, usually beginning in infancy. The fever episodes are typically accompanied by poor feeding, vomiting, and diarrhea, and can lead to hospitalization. In many affected individuals, the episodes occur regularly, arising approximately every 2 to 4 weeks and lasting 5 to 7 days, although the frequency can decrease with age.\n\nMany people with TRNT1 deficiency have an immune system disorder (immunodeficiency) that can lead to recurrent bacterial infections. Repeated infections can cause life-threatening damage to internal organs. The immunodeficiency is characterized by low numbers of immune system cells called B cells, which normally help fight infections by producing immune proteins called antibodies (or immunoglobulins). These proteins target foreign invaders such as bacteria and viruses and mark them for destruction. In many individuals with TRNT1 deficiency, the amount of immunoglobulins is also low (hypogammaglobulinemia).\n\nA common feature of TRNT1 deficiency is a blood condition called sideroblastic anemia, which is characterized by a shortage of red blood cells (anemia). In TRNT1 deficiency, the red blood cells that are present are unusually small (erythrocytic microcytosis). In addition, developing red blood cells in the bone marrow (erythroblasts) can have an abnormal buildup of iron that appears as a ring of blue staining in the cell after treatment in the lab with certain dyes. These abnormal cells are called ring sideroblasts.\n\nNeurological problems are also frequent in TRNT1 deficiency. Many affected individuals have delayed development of speech and motor skills, such as sitting, standing, and walking, and some have low muscle tone (hypotonia).\n\nEye abnormalities, often involving the light-sensing tissue at the back of the eye (the retina), can occur in people with TRNT1 deficiency. Some of these individuals have a condition called retinitis pigmentosa, in which the light-sensing cells of the retina gradually deteriorate. Eye problems in TRNT1 deficiency can lead to vision loss.\n\nFeatures that occur less commonly in people with TRNT1 deficiency include hearing loss caused by abnormalities of the inner ear (sensorineural hearing loss), recurrent seizures (epilepsy), and problems with the kidneys or heart.\n\nTRNT1 deficiency is a condition that affects many body systems. Its signs and symptoms can involve blood cells, the immune system, the eyes, and the nervous system. The severity of the signs and symptoms vary widely.