Progressive cerebellar atrophy and polyneuropathy: expanding the spectrum of PNKP mutations.

We present a neurodegenerative disorder starting in early childhood of two brothers consisting of severe progressive polyneuropathy, severe progressive cerebellar atrophy, microcephaly, mild epilepsy, and intellectual disability. The cause of this rare syndrome was found to be a homozygous mutation (c.1250_1266dup, resulting in a frameshift p.Thr424GlyfsX48) in PNKP, identified by applying homozygosity mapping and whole-genome sequencing. Mutations in PNKP have previously been associated with a syndrome of microcephaly, seizures and developmental delay (MIM 613402), but not with a neurodegenerative disorder. PNKP is a dual-function enzyme with a key role in different pathways of DNA damage repair. DNA repair disorders can result in accelerated cell death, leading to underdevelopment and neurodegeneration. In skin fibroblasts from both affected individuals, we show increased susceptibility to apoptosis under stress conditions and reduced PNKP expression. PNKP is known to interact with DNA repair proteins involved in the onset of polyneuropathy and cerebellar degeneration; therefore, our findings explain this novel phenotype.

The monocyte transcriptome during pregnancy in multiple sclerosis: prominent expression of the Fc-receptor CD64.

BACKGROUND: During the third trimester of pregnancy multiple sclerosis (MS) disease activity is reduced. It is not fully understood which factors mediate this disease amelioration. OBJECTIVE: To study alterations of the monocyte transcriptome during pregnancy in MS patients, using a genomewide approach to identify differentially regulated genes. METHODS: Women with MS and healthy controls were longitudinally studied, including a visit before pregnancy. RESULTS: RNA-microarray analysis was performed in six patients. We found a significant increase of CD64 (Fc gamma receptor 1a, FcgR1a) during the third trimester compared with baseline, confirmed by RT-PCR in a group of ten patients. Analysis with Ingenuity software was performed using all genes expression of which was altered at least 1.5-fold in at least five out of six patients. Major networks that were altered during MS pregnancy were: cell-to-cell signalling and interaction, immune response, and cell signalling. From the genes selected for Ingenuity analysis, seven additional candidate genes, selected for their biological interest, were tested using RT-PCR in ten patients with MS and nine controls. We found an increased expression of JAK2 and STAT1 directly postpartum in patients with MS and in controls. CONCLUSION: The increased CD64 expression during pregnancy is indicative of enhanced innate immune functions.