Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0026827 (hypotonia)
 5,860 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Hyperphosphatasia-mental retardation syndrome is a recently delineated disorder associated with a recognizable facial phenotype and brachytelephalangy. This autosomal recessive condition is caused by homozygous and compound heterozygous missense mutations of PIGV, encoding a member of the GPI-anchor biosynthesis pathway. Here, we report on two further, unrelated patients with developmental delay, elevated serum levels of AP, distinctive facial features, hypoplastic terminal phalanges, anal atresia in one and Hirschsprung disease in the other patient. By sequencing PIGV we detected compound heterozygous mutations c.467G>A and c.1022C>A in Patient 1 and a homozygous mutation c.1022C>A in Patient 2. We reviewed the eight reported cases with proven PIGV mutations and re-defined the phenotypic spectrum associated with PIGV mutations: intellectual disability, the distinct facial gestalt, brachytelephalangy, and hyperphosphatasia are constant features but also anorectal malformations and Hirschsprung disease as well as cleft lip/palate and hearing impairment should be considered as part of the clinical spectrum. Moreover, seizures and muscular hypotonia are frequently associated with PIGV mutations.
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PMID:Hyperphosphatasia-mental retardation syndrome due to PIGV mutations: expanded clinical spectrum. 2173 89

Recently, mutations in genes involved in the biosynthesis of the glycosylphosphatidylinositol (GPI) anchor have been identified in a new subclass of congenital disorders of glycosylation (CDGs) with a distinct spectrum of clinical features. To date, mutations have been identified in six genes (PIGA, PIGL, PIGM, PIGN, PIGO, and PIGV) encoding proteins in the GPI-anchor-synthesis pathway in individuals with severe neurological features, including seizures, muscular hypotonia, and intellectual disability. We developed a diagnostic gene panel for targeting all known genes encoding proteins in the GPI-anchor-synthesis pathway to screen individuals matching these features, and we detected three missense mutations in PGAP2, c.46C>T, c.380T>C, and c.479C>T, in two unrelated individuals with hyperphosphatasia with mental retardation syndrome (HPMRS). The mutations cosegregated in the investigated families. PGAP2 is involved in fatty-acid GPI-anchor remodeling, which occurs in the Golgi apparatus and is required for stable association between GPI-anchored proteins and the cell-surface membrane rafts. Transfection of the altered protein constructs, p.Arg16Trp (NP_001243169.1), p.Leu127Ser, and p.Thr160Ile, into PGAP2-null cells showed only partial restoration of GPI-anchored marker proteins, CD55 and CD59, on the cell surface. In this work, we show that an impairment of GPI-anchor remodeling also causes HPMRS and conclude that targeted sequencing of the genes encoding proteins in the GPI-anchor-synthesis pathway is an effective diagnostic approach for this subclass of CDGs.
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PMID:PGAP2 mutations, affecting the GPI-anchor-synthesis pathway, cause hyperphosphatasia with mental retardation syndrome. 2356 47