WD repeat domain phosphoinositide-interacting protein 4 (WIPI-4) is a protein that in humans is encoded by the WDR45 gene. Mutations in this gene cause a distinct form of Neurodegeneration with brain iron accumulation (NBIA) called Beta-propeller protein-associated neurodegeneration (BPAN). Function
WIPI-4 is a member of the WD repeat protein family. WD repeats are minimally conserved regions of approximately 40 amino acids typically bracketed by gly-his and trp-asp (GH-WD), which may facilitate formation of heterotrimeric or multiprotein complexes. Members of this family are involved in a variety of cellular processes, including cell cycle progression, signal transduction, apoptosis, and gene regulation. This gene WDR45 has a pseudogene at chromosome 4q31.3. Multiple alternatively spliced transcript variants encoding distinct isoforms have been found for this gene, but the biological validity and full-length nature of some variants have not been determined. Role in disease
De novo loss of function mutations in WDR45 were identified by exome sequencing in 20 patients with progressive neurodegeneration and evidence of iron on brain MRI scans. The mutations cause an X-linked dominant form of NBIA now called Beta-propeller protein-associated neurodegeneration (BPAN). A name for the disease before the gene was identified was called static encephalopathy of childhood with neurodegeneration in adulthood (SENDA), though this term is no longer used. There are no current treatments for BPAN, though medications and therapies can be used to treat symptoms. See also
WIPI protein family

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== Further reading ==
Optic nerve glioma (or optic glioma), a form of glioma which affects the optic nerve, is often one of the central nervous system manifestations of neurofibromatosis 1.Optic gliomas are usually pilocytic tumors, and can involve the optic nerve or optic chiasm. Optic gliomas are usually associated with neurofibromatosis type 1 in 30% of people with the condition.Optic nerve gliomas have low mortality but extremely high prevalence of vision loss & eye-bulging exophthalmos) in children. As of 2014, approximately 1000 cases had been reported. Diagnosis
Optic nerve gliomas are diagnosed using magnetic resonance imaging (MRI) and CT scans. The tumor adopts a fusiform appearance, appearing wider in the middle and tapered at the ends. Enlargement of the optic nerve along with a downward kink in the mid-orbit is usually observed. While CT scans allow for optic nerve evaluation, MRI allows for intracranial evaluation to observe if the tumor has extended to other regions such as the optic chiasm & hypothalamus. Treatment
The main goal of treating optic gliomas is to preserve vision for as long as possible. The tumor’s slow & self-limiting growth indicates that it is not immediately problematic in most benign cases, with long-term studies showing that people with optic glioma may still have stable functional vision without intervention. As a result, the first & preferred course of action is usually observation of optic glioma over time.Once the first signs of visual deterioration and/or tumor progression are observed, interventional treatments will then commence. These include radiation therapy, [[chemotherapy and surgical excision.