Mutations in PURA cause profound neonatal hypotonia, seizures, and encephalopathy in 5q31.3 microdeletion syndrome

Abstract

5q31.3 microdeletion syndrome is characterized by neonatal hypotonia, encephalopathy with or without epilepsy, and severe developmental delay, and the minimal critical deletion interval harbors three genes. We describe 11 individuals with clinical features of 5q31.3 microdeletion syndrome and de novo mutations in PURA, encoding transcriptional activator protein Pur-α, within the critical region. These data implicate causative PURA mutations responsible for the severe neurological phenotypes observed in this syndrome.

Figure 1

PURA Mutations in the Affected Human Subjects and Functions of the PURA Ortholog in Model System C. elegans (A) PURA is located in chromosomal region 5q31.2 (according to the UCSC Genome Browser). A single exon (blue) encodes a protein with three PUR motifs, as shown in green. On the protein diagram, missense and in-frame-deletion mutations are brown, and the truncating mutations are shown in red. (B) Six subjects with de novo PURA mutations are shown. The craniofacial features are mainly characterized by myopathic facies. For whom clinical photographs are shown, informed consent specifically agreeing to publish these photographs in medical publications was obtained. (C) DNA staining in the germline of a wild-type C. elegans animal. Yellow dashed lines indicate differentiated oocytes. (D) Oocytes were absent in the plp-1-mutant animal with smaller gonads. Wild-type (N2) and RB1711 (plp-1(ok2155)IV) animals were obtained from the Caenorhabditis Genetics Center. C. elegans were grown on standard nematode growth media plates (containing 5 mg/l cholesterol) with E. coli OP50 at 25°C according to standard protocols. DAPI staining was performed at room temperature. The germline was dissected out from young adult worms. (E) Average speed of individual worm movement (wild-type n = 14, plp-1 n = 12). The p value was obtained by a one-tailed Student’s t test. Error bars in the scattered dot plot represent the mean and the SEM. Spontaneous movement of age-synchronized worms on standard worm plates was recorded for 15 s with an SMZ1500 stereo microscope (Nikon) connected to a C11440 camera (Hamamatsu). Individual worms were tracked with NIS Elements AR 2D tracking imaging software (Nikon), and the average velocity (μm/s) was calculated. Representative recording of wild-type worms and plp-1 mutants are shown in Movies S1 and S2, respectively.