MedGen

An abnormally low number of neutrophils in the peripheral blood. [from HPO]

An abnormal decreased number of leukocytes in the blood. [from HPO]

Marked decrease in the number of granulocytes. [from HPO]

A disease involving leukocytes. [from MONDO]

PI4KA-related disorder is a clinically variable disorder characterized primarily by neurologic dysfunction (limb spasticity, developmental delay, intellectual disability, seizures, ataxia, nystagmus), gastrointestinal manifestations (multiple intestinal atresia, inflammatory bowel disease), and combined immunodeficiency (leukopenia, variable immunoglobulin defects). Age of onset is typically antenatal or in early childhood; individuals can present with any combination of these features. Rare individuals present with later-onset hereditary spastic paraplegia. Brain MRI findings can include hypomyelinating leukodystrophy, cerebellar hypoplasia/atrophy, thin or dysplastic corpus callosum, and/or perisylvian polymicrogyria. [from GeneReviews]

5-fluorouracil is a chemotherapeutic agent, and a member of the fluoropyrimidine group of substances. It is mainly used to treat solid tumors, such as colorectal, breast and aerodigestive cancers. Dihydropyrimidine dehydrogenase (DPD, encoded by the DPYD gene) is the rate-limiting enzyme for fluoropyrimidine metabolism and is therefore responsible for the detoxification of these types of drugs. Patients who are homozygous for variants in DPYD that lead to a non-functional protein, such as *2A or *13, have a high risk of severe or fatal drug toxicities and may benefit from receiving an alternative chemotherapeutic drug. Patients heterozygous for these variants also have an increased risk for drug toxicities, and reduced dosing is recommended for these individuals. Guidelines regarding the use of pharmacogenomic tests in dosing for 5-fluorouracil have been published in Clinical Pharmacology and Therapeutics by the Clinical Pharmacogenetics Implementation Consortium (CPIC) and are available on the PharmGKB website. [from PharmGKB]