New Single Nucleotide Deletion In the SMPD1 Gene Causes Niemann Pick Disease Type A in a Child from Southwest Iran: A Case Report

Niemann Pick disease (NPD) type A (NPA: MIM #257200) is a lipid storage disorder with an autosomal recessive inheritance and occurrs by defect of the SMPD1 gene encoding sphingomyelinase. Disruption of this enzyme leads to the accumulation of sphingomyelin in brain and liver, which in turn causes dysfunction or damage of tissue. We report firstly a 2.5 year old boy with NPA in southwest Iran. Initially, the diagnosis was resulted on the basis of clinical symptoms. The genomic DNA of the suspected individual was subjected to exon sequencing of the SMPD1 gene. According to the human reference sequence NM_000543.4, a novel single guanine deletion resulting in a frameshift mutation (p.Gly247Alafs*9) was observed in the SMPD1 gene that might be causative for the outcome of the disease. The present report is the first molecular genetics diagnosis of the NPA in southwest Iran. The detected deletion in the SMPD1 gene is remarkable because of its novelty. Despite similar morbidity SGA infants exhibited higher lethal complication rates following delayed meconium passage compared to AGA infants.