Infantile spasms in early-onset Niemann-Pick disease with a novel compound heterozygous mutations in SMPD1 gene
NEW HORIZONS IN TRANSLATIONAL MEDICINE
Authors: Chetta, Massimiliano; Guacci, Anna; Rizzo, Francesca; Marchese, Giovanna; Operto, Francesca Felicia; Weisz, Alessandro; Coppola, Giangennaro
Abstract
Niemann-Pick diseases are a group of rare autosomal recessive disorders caused by an inherited deficiency of lysosomal storage with similar clinical presentations. At least three different Niemann-Pick (NP) diseases have been described, with NPA and NPB occurring as a result of a deficiency of the acid sphingomyelinase (ASM) enzyme, while NPC as a disorder that cause misregulation in cholesterol and lipids turnover, causing their accumulation in various tissues, including brain. The resulting phenotypic spectrum ranges from a severe infantile type with neurologic degeneration and death, usually by 3 years of age (NPA), to a non-neurologic adult onset form compatible with survival into adulthood (NPB) and a neurovisceral disorder with symptoms that occur at different times and progress independently (NPC). Here, we report on an Italian child born from non-consanguineous healthy parents, with a negative family history, who developed infantile spasms at the age of 5 months and clinical signs of potential storage disease. The genetic screening, performed by means of whole exome sequencing, revealed compound heterozygous mutations in the Sphingomyelin Phosphodiesterase 1 gene (SMPD1), comprising both a homozygous polymorphism (p.V36A) in exon 1 and a new frameshift heterozygous deletion (c.1187delT) in exon 3 generating a premature stop (TAA) at codon 424 (p.L395fsX29). This result appears to corroborate the phenotypic heterogeneity of the symptoms and suggests a correlation between the presence of a truncated SMPD1 polypeptide and the very early onset of the disease. Focal points center dot Benchside: The comprehension of genotype-phenotype correlations in patients affected by Niemann-Pick disease will accelerate the accuracy of the diagnosis and permit to ameliorate patient follow-up. center dot Bedside: The coexistence of a homozygous polymorphism and of a new heterozygous frameshift deletion in exon 3 of the SMPDI gene reveals the presence of infantile spasms, not previously related to mutations in SMPDI gene. Elucidating the mechanisms associated to this altered gene product could open novel approaches in therapy. (C) 2016 European Society for Translational Medicine. Published by Elsevier Ltd. All rights reserved.
Homozygous pArg610del Mutation Unusually Associated With Severe Delay of Growth in 2 Acid Sphingomyelinase Deficiency-affected Sibs
JOURNAL OF PEDIATRIC HEMATOLOGY ONCOLOGY
Authors: Naifar, Manel; Kallel, Faten; HadjKacem, Faten; Boudabous, Hela; Kallel, Rim; Boudawara, Tahia; Messaoud, Olfa; Tbib, Neji; Charfi, Nadia; Abid, Mohamed; Froissart, Roseline; Messedi, Sondes Hdiji; Ayedi, Fatma
Abstract
Background:Typically, patients with Acid Sphingomyelinase Deficiency (ASMD) because of p.Arg610del mutation, have mild phenotype with normal linear growth.Observation:We reported the case of 2 Tunisian brothers who have been referred for splenomegaly, polyadenopathies, pubertal, and growth delay. Molecular testing of SMPD1 gene revealed the presence of a homozygous p.Arg610del mutation. Lysosphingomyelin and its isoform-509 were both increased confirming ASMD for both cases. Growth hormone deficiency was highly suspected but growth hormone response after stimulating tests was acceptable for both patients.Conclusions:There is no correlation between phenotype-genotype in case of p.Arg610del mutation that could be associated to a severe delay of growth.