Two case reports of a novel missense mutation in the PNPLA6 gene in two siblings with chorioretinal dystrophy, hypogonadotropic hypogonadism, and cerebellar ataxia.

BACKGROUND: Boucher Neuhäuser Syndrome (BNS) is a rare disease with autosomal recessive inheritance defined by the classical triad; early-onset ataxia, hypogonadism and chorioretinal dystrophy. CASE PRESENTATION: We present two siblings diagnosed with BNS at midlife, identified with homozygous state of a novel PNPLA6 missense mutation. One healthy sibling and the mother were heterozygous carriers of the mutation. The proband presented with the classical triad and the other sibling presented with visual problems at first. The proband was referred to our department by a private Neurologist, in early adulthood, because of hypogonadism, cerebellar ataxia, axonal neuropathy, and chorioretinal dystrophy for further evaluation. The sibling was referred to our department for evaluation, at childhood, due to visual problems. Later, the patient displayed the triad of ataxia, hypogonadotropic hypogonadism, and chorioretinal dystrophy. The unusual medical history of the two siblings led to further examinations and eventually the diagnosis of the first BNS cases in Cyprus. WES-based ataxia in silico gene panel analysis revealed 15 genetic variants and further filtering analysis revealed the PNPLA6 c.3323G > A variant. Segregation analysis in the family with Sanger sequencing confirmed the PNPLA6 homozygous variant c.3323G > A, p.Arg1108Gln in exon 29. CONCLUSIONS: This highlights the importance of considering rare inherited causes of visual loss, spinocerebellar ataxia, or/and HH in a neurology clinic and the significant role of genetic sequencing in the diagnostic process.

Novel variants in PNPLA6 causing syndromic retinal dystrophy.

PNPLA6-related disorders include several phenotypes, such as Boucher-Neuhäuser syndrome, Gordon Holmes syndrome, spastic paraplegia, photoreceptor degeneration, Oliver-McFarlane syndrome and Laurence-Moon syndrome. In this study, detailed clinical evaluations and genetic testing were performed in five (4 Chinese and 1 Caucasian/Chinese) syndromic retinal dystrophy patients. Genotype-phenotype correlations were analyzed based on review of the literatures of previously published PNPLA6-related cases. The mean age of patients and at first visit were 20.8 years (11, 12, 25, 28, 28) and 14.2 years (4, 7, 11, 24, 25), respectively. They all presented with severe chorioretinal dystrophy and profoundly decreased vision. The best corrected visual acuity (BCVA) ranged from 20/200 to 20/2000. Systemic manifestations included cerebellar ataxia, hypogonadotropic hypogonadism and hair anomalies. Six novel and three reported pathogenic variants in PNPLA6 (NM_001166111) were identified. The genotypes of the five cases are: c.3134C > T (p.Ser1045Leu) and c.3846+1G > A, c.3547C > T (p.Arg1183Trp) and c.1841+3A > G, c.3436G > A (p.Ala1146Thr) and c.2212-10A > G, c.3436G > A (p.Ala1146Thr) and c.2266C > T (p.Gln756*), c.1238_1239insC (p.Leu414Serfs*28) and c.3130A > G (p.Thr1044Ala). RT-PCR confirmed that the splicing variants indeed led to abnormal splicing. Missense variants p.Thr1044Ala, p.Ser1045Leu, p.Ala1146Thr, p.Arg1183Trp and c.3846+1G > A are located in Patatin-like phospholipase (Pat) domain. In conclusion, we report the phenotypes in five patients with PNPLA6 associated syndromic retinal dystrophy with variable systemic involvement and typical choroideremia-like fundus changes. Ocular manifestations may be the first and the only findings for years. All of our patients carried one severe deleterious variant (stop-gain or splicing variant) and one milder variant (missense variant). Retinal involvement was significantly correlated with severe deleterious variants and variants in Pat domain.

A novel PNPLA6 mutation in a Turkish family with intractable Holmes tremor and spastic ataxia.

Autosomal recessive cerebellar ataxias are a group of rare neurological diseases with a genetic origin. Recently, the mutations in the PNPLA6 gene were suggested to lead to ataxia and also to other specific syndromes such as Boucher-Neuhauser (ataxia, hypogonadism, and chorioretinal dystrophy) or Gordon-Holmes Syndromes (ataxia, hypogonadism, and brisk reflexes) within a broad spectrum of neurodegenerative diseases. Here we report three patients from a single-family with a novel pathogenic mutation in the PNPLA6 gene which led to predominantly spastic-ataxia, and intractable Holmes tremor. The PNPLA6-related disease should be considered in the differential diagnosis of spastic-ataxias even in the absence of chorioretinal dystrophy, and hypogonadotropic hypogonadism. Further studies should unravel the factors which account for the phenotypic variability present in patients with PNPLA6 gene mutations.

Loss of swiss cheese in Neurons Contributes to Neurodegeneration with Mitochondria Abnormalities, Reactive Oxygen Species Acceleration and Accumulation of Lipid Droplets in Drosophila Brain.

Various neurodegenerative disorders are associated with human NTE/PNPLA6 dysfunction. Mechanisms of neuropathogenesis in these diseases are far from clearly elucidated. Hereditary spastic paraplegia belongs to a type of neurodegeneration associated with NTE/PNLPLA6 and is implicated in neuron death. In this study, we used Drosophila melanogaster to investigate the consequences of neuronal knockdown of swiss cheese (sws)-the evolutionarily conserved ortholog of human NTE/PNPLA6-in vivo. Adult flies with the knockdown show longevity decline, locomotor and memory deficits, severe neurodegeneration progression in the brain, reactive oxygen species level acceleration, mitochondria abnormalities and lipid droplet accumulation. Our results suggest that SWS/NTE/PNPLA6 dysfunction in neurons induces oxidative stress and lipid metabolism alterations, involving mitochondria dynamics and lipid droplet turnover in neurodegeneration pathogenesis. We propose that there is a complex mechanism in neurological diseases such as hereditary spastic paraplegia, which includes a stress reaction, engaging mitochondria, lipid droplets and endoplasmic reticulum interplay.

Different Cerebellar Ataxia Phenotypes Associated with Mutations of the PNPLA6 Gene in Brazilian Patients with Recessive Ataxias.

Autosomal recessive cerebellar ataxias (ARCAs) represent a heterogeneous group of inherited disorders. The association of early-onset cerebellar ataxia with hypogonadotropic hypogonadism is related to two syndromes, known as Gordon Holmes syndrome (GHS-ataxia and pyramidal signs with hypogonadotropic hypogonadism) and Boucher-Neuhäuser syndrome (BNS-ataxia with chorioretinal dystrophy). Mutations in the PNPLA6 gene have been identified as the cause of hereditary spastic paraplegia and complex forms of ataxia associated with retinal and endocrine manifestations. We reported two Brazilian patients with sporadic, progressive cerebellar ataxia, associated with hypogonadotropic hypogonadism, in whom the GHS and BNS were confirmed by the demonstration of compound heterozygote mutations in the PNPLA6 gene. Genetic analysis of the patient 1 revealed compound heterozygous mutations, one allele in exon 34 and the other allele in exon 29. Genetic exam of the patient 2 also demonstrated compound heterozygous mutations. Three were novel mutations. The missense mutation c.3373G> A, found in the BNS patient, was previously related to Oliver-McFarlane syndrome. These different mutations in this gene suggest a complex phenotype associated disease spectrum.

Pure Cerebellar Ataxia with Homozygous Mutations in the PNPLA6 Gene.

Autosomal-recessive cerebellar ataxias (ARCA) are clinically and genetically heterogeneous conditions primarily affecting the cerebellum. Mutations in the PNPLA6 gene have been identified as the cause of hereditary spastic paraplegia and complex forms of ataxia associated with retinal and endocrine manifestations in a field where the genotype-phenotype correlations are rapidly expanding. We identified two cousins from a consanguineous family belonging to a large Zoroastrian (Parsi) family residing in Mumbai, India, who presented with pure cerebellar ataxia without chorioretinal dystrophy or hypogonadotropic hypogonadism. We used a combined approach of clinical characterisation, homozygosity mapping, whole-exome and Sanger sequencing to identify the genetic defect in this family. The phenotype in the family was pure cerebellar ataxia. Homozygosity mapping revealed one large region of shared homozygosity at chromosome 19p13 between affected individuals. Within this region, whole-exome sequencing of the index case identified two novel homozygous missense variants in the PNPLA6 gene at c.3847G>A (p.V1283M) and c.3929A>T (p.D1310V) in exon 32. Both segregated perfectly with the disease in this large family, with only the two affected cousins being homozygous. We identified for the first time PNPLA6 mutations associated with pure cerebellar ataxia in a large autosomal-recessive Parsi kindred. Previous mutations in this gene have been associated with a more complex phenotype but the results here suggest an extension of the associated disease spectrum.

Mutational analysis of the CYP7B1, PNPLA6 and C19orf12 genes in autosomal recessive hereditary spastic paraplegia.

The hereditary spastic paraplegias (HSPs) comprise a group of genetically heterogeneous neurodegenerative diseases. Here, we evaluated the spectrum and frequency of mutations in the CYP7B1, PNPLA6 and C19orf12 genes (causative for the subtypes SPG5A, SPG39 and SPG43, respectively) in a cohort of 63 unrelated HSP patients with suspected autosomal recessive inheritance. Two novel homozygous mutations (one frameshift and one missense mutation) were detected in CYP7B1 (SPG5A), while no disease-causing mutation was identified for SPG39 or SPG43.

Association of sick building syndrome with neuropathy target esterase (NTE) activity in Japanese.

Sick building syndrome (SBS) is a set of several clinically recognizable symptoms reported by occupants of a building without a clear cause. Neuropathy target esterase (NTE) is a membrane bound serine esterase and its reaction with organophosphates (OPs) can lead to OP-induced delayed neuropathy (OPIDN) and nerve axon degeneration. The aim of our study was to determine whether there was a difference in NTE activity in the peripheral blood mononuclear cells (PBMCs) of Japanese patients with SBS and healthy controls and whether PNPLA6 (alias NTE) gene polymorphisms were associated with SBS. We found that the enzymatic activity of NTE was significantly higher (P < 0.0005) in SBS patients compared with controls. Moreover, population with an AA genotype of a single nucleotide polymorphism (SNP), rs480208, in intron 21 of the PNPLA6 gene strongly reduced the activity of NTE. Fifty-eight SNP markers within the PNPLA6 gene were tested for association in a case-control study of 188 affected individuals and 401 age-matched controls. Only one SNP, rs480208, was statistically different in genotype distribution (P = 0.005) and allele frequency (P = 0.006) between the cases and controls (uncorrected for testing multiple SNP sites), but these were not significant by multiple corrections. The findings of the association between the enzymatic activity of NTE and SBS in Japanese show for the first time that NTE activity might be involved with SBS.

PNPLA6 disorders: what's in a name?

BACKGROUND: Variants in the patatin-like phospholipase domain containing 6 (PNPLA6) gene cause a broad spectrum of neurological disorders characterized by gait disturbance, visual impairment, anterior hypopituitarism, and hair anomalies. This review examines the clinical, cellular, and biochemical features found across the five PNPLA6-related diseases, with a focus on future questions to be addressed. MATERIALS AND METHODS: A literature review was performed on published clinical reports on patients with PNPLA6 variants. Additionally, in vitro and in vivo models used to study the encoded protein, Neuropathy Target Esterase (NTE), are summarized to lend mechanistic perspective to human diseases. RESULTS: Biallelic pathogenic PNPLA6 variants cause five systemic neurological disorders: spastic paraplegia type 39, Gordon-Holmes, Boucher-Neuhäuser, Laurence-Moon, and Oliver-McFarlane syndromes. PNPLA6 encodes NTE, an enzyme involved in maintaining phospholipid homeostasis and trafficking in the nervous system. Retinal disease presents with a unique chorioretinal dystrophy that is phenotypically similar to choroideremia and Leber congenital amaurosis. Animal and cellular models support a loss-of-function mechanism. CONCLUSIONS: Clinicians should be aware of choroideremia-like ocular presentation in patients who also experience growth defects, motor dysfunction, and/or hair anomalies. Although NTE biochemistry is well characterized, further research on the relationship between genotype and the presence or absence of retinopathy should be explored to improve diagnosis and prognosis.

DNA Methylation of Patatin-Like Phospholipase Domain-Containing Protein 6 Gene Contributes to the Risk of Intracranial Aneurysm in Males.

Objective: This study is aimed to investigate the contribution of patatin-like phospholipase domain-containing protein 6 (PNPLA6) DNA methylation to the risk of intracranial aneurysm (IA) in the Han Chinese population. Methods: A total of 96 age- and sex-matched participants were recruited to evaluate PNPLA6 methylation via bisulfite pyrosequencing. The PNPLA6 mRNA expression in the plasma was determined using real-time quantitative reverse transcription-polymerase chain reaction. Human primary artery smooth muscle cells (HPCASMC) were used for the in vitro function study. Results: PNPLA6 methylation was significantly higher in patients with IA than in healthy controls (p < 0.01). Sex group analysis showed that this correlation appeared in the male group (p < 0.01) but not in the female group (p > 0.05). PNPLA6 methylation was significantly associated with age in all participants (r = 0.306, p = 0.003) and in the control group (r = 0.377, p = 0.008) but not in the IA group (r = 0.127, p = 0.402). Furthermore, the PNPLA6 mRNA expression significantly decreased in patients with IA than that in the controls (p = 0.016). PNPLA6 expression was significantly inversely correlated with elevated DNA methylation in participants (r = -0.825, p < 0.0001). In addition, PNPLA6 transcription was significantly enhanced following treatment with 5-aza-2'-deoxycytidine methylation inhibitor in HPCASMC.The receiver operating characteristic analyses of curves showed that the PNPLA6 mean methylation [area under the curve (AUC) = 0.74, p < 0.001] and mRNA expression (AUC = 0.86, p < 0.001) could have a diagnostic value for patients with IA. Conclusion: Although future functional experiments are required to test our hypothesis, our study demonstrated that PNPLA6 methylation and mRNA expression were significantly associated with the risk of IA; thus, they show potential for use in the early diagnosis of IA.

Identification of Novel Compound Heterozygous Variants of the PNPLA6 Gene in Boucher-Neuhäuser Syndrome.

Background: Boucher-Neuhäuser syndrome (BNS, MIM 215470) is a rare autosomal recessive syndrome caused by mutations in the PNPLA6 gene. Few BNS cases have been reported for functional validation at the RNA level. Herein, we report on the family of a 17-year-old girl with clinical characteristics of BNS, genetic validation, and a systematic review of PNPLA6 variants related to BNS. Methods: Clinical data and blood samples were collected from the patient and their parents, and whole-exome sequencing was performed and confirmed by Sanger sequencing. RNA-sequencing (RNA-Seq) and quantitative RT-PCR (qRT-PCR) were performed, and the three-dimensional protein structures of the variants were predicted. Results: We report a 17-year-old female with progressive night blindness since the age of four, primary amenorrhea, and non-development of secondary sexual characteristics. Her impaired vision was diagnosed as retinal pigmentary degeneration of the retina. She had congenital hypogonadotropic hypogonadism (CHH) but no cerebellar ataxia at present. Two novel compound heterozygous variants (c.2241del/p.Met748TrpfsTer65 and c.2986A>G/p.Thr996Ala) of the PNPLA6 gene (NM_006702.4) were identified by whole-exome sequencing. The former variant was carried from her healthy father and has not been reported previously. The latter was inherited from her healthy mother and was noted in a report without functional studies. The RT-PCR results showed that the mRNA expression of PNPLA6 was lower in this patient and her father than in the control group. She was diagnosed with BNS. Both variants (c.2241del and c.2986A>G) were likely pathogenic according to the ACMG criteria. The novel variants in the PNPLA6 gene related to Boucher-Neuhäuser syndrome were summarized in this article. Conclusion: The possibility of Boucher-Neuhäuser syndrome should be considered when patients present with night blindness, impaired vision, and hypogonadotropic hypogonadism. Gene sequencing is currently the primary diagnostic method. Herein, novel compound heterozygous variants of PNPLA6 were identified in a BNS patient, and its function was verified at the RNA level. The PNPLA6 c.2241del variant is novel and potentially pathogenic, expanding the mutation spectrum in PNPLA6.

Neuropsychological assessment of Boucher-Neuhäuser syndrome: A case report.

OBJECTIVE: Boucher-Neuhäuser Syndrome (BNS) is a rare autosomal recessive disorder characterized by hypogonadotropic hypogonadism, spinocerebellar ataxia, and chorioretinal syndrome, and associated with a variant in the PNPLA6 gene. Although many reports have mentioned the presence of cognitive impairment, a neuropsychological assessment of a BNS case has never been published. Here, we provide a detailed description of a young adult patient with BNS who has a homozygous pathogenic variant in the PNPLA6 gene. METHOD: A 21-year-old man with progressive ataxia and a history of hypogonadotropic hypogonadism and chorioretinal dystrophy was diagnosed with BNS. A comprehensive cognitive evaluation was performed, requiring the ad hoc selection and adaption of neuropsychological tests to overcome visual and motor impairments that characterize this syndrome. RESULTS: The patient presented an intact global cognitive profile with selective executive dysfunction and mild verbal reasoning dysfunction. In particular, attentional-inhibitory control, working memory, and set switching were impaired, and inadequate development of conceptual knowledge and abstract reasoning was observed. CONCLUSIONS: This is the first report of an explicitly documented comprehensive neuropsychological assessment in a patient with BNS. The battery we composed is an example of a methodology that can be used to conduct a detailed cognitive examination without being penalized for physical impairment.Further studies are needed to define the typical cognitive features that characterize BNS and possibly identify its cognitive phenotype(s).

Novel phenotype with prominent cerebellar oculomotor dysfunction in spastic paraplegia type 39.

OBJECTIVES: The term hereditary spastic paraplegia comprises an ever-expanding array of neurological disorders with distinct aetiologies. Spastic paraplegia gene 39 is one of the many genetically defined types with features of other organs and neurological systems in addition to paraspasticity. We describe a large kindred with a novel clinical phenotype as, in addition to spastic paraplegia, affected subjects suffered from a prominent cerebellar oculomotor dysfunction with two hitherto undescribed mutations of PNPLA6. METHODS: Three of five genetically tested family members of a large kindred were affected by spastic gait and a unique and prominent cerebellar oculomotor dysfunction. Further clinical, imaging, laboratory and videonystagmographic data were analyzed. Genetic analysis was done using next-generation sequencing. RESULTS: The most salient clinical feature, in addition to paraspasticity, in three of five subjects was cerebellar oculomotor dysfunction with an upbeating nystagmus provoked by downward gaze. Genetic analysis revealed two hitherto unknown sequence variants in the PNPLA6 gene, a splice-site variant c.1635 + 3G > T and a missense variant c.3401A > T, p.(Asp1134Val). In addition to cerebellar oculomotor dysfunction, compound-heterozygous siblings presented with paraspasticity and a moderate hypogonadotropic hypogonadism in the female. A paternal uncle being homozygous for the splice-site variant of PNPLA6 presented with increased lower limb reflexes and an unstable gait. Treatment with 4-aminopyridine, a potassium channel blocker, lead to meaningful improvement of clinical symptoms. CONCLUSIONS: The unique and prominent cerebellar ocular motor disorder in our family broadens the spectrum of clinical phenotypes associated with variations in the PNLA6 gene. The finding of paraspasticity with cerebellar oculomotor dysfunction alongside inconspicuous brainstem imaging may raise suspicion of complex HSP with PNPLA6 mutations.

Chorioretinal dystrophy, hypogonadotropic hypogonadism, and cerebellar ataxia: Boucher-Neuhauser syndrome due to a homozygous (c.3524C>G (p.Ser1175Cys)) variant in PNPLA6 gene.

Purpose: The current study aims to raise awareness of Boucher - Neuhauser syndrome (BNHS) that occurs as a rare phenotype due to biallelic pathogenic variants in the PNPLA6 gene.Methods: Detailed family histories and clinical data were recorded. Whole exome sequencing was performed and co-segregation analysis of the family was done by sanger sequencing. Also, review of 28 molecularly confirmed patients with BNHS from the literature was evaluated.Results: We identified a missense homozygous variant (c.3524 C > G (p.Ser1175Cys)) in the PNPLA6 gene, which explains the phenotype of the patient and neurologic, ophthalmologic, endocrine, and genetic evaluations established a diagnosis of BNHS. Symptoms, ethnicity, clinical and genetic findings of 28 molecularly confirmed patients with BNHS from the literature were also presented.Conclusion: We present the main findings of a Turkish family with BNHS together with detailed clinical and genetic profiles of patients diagnosed as BNHS that have been molecularly confirmed in the literature so far.

Oliver McFarlane syndrome: two new cases and a review of the literature.

BACKGROUND: Oliver McFarlane syndrome is a rare syndrome. Clinical presentations include trichomegaly, chorioretinal degeneration, pituitary hormone deficits, and neurological manifestations. Genetic analysis has recently placed this syndrome within the group of PNPLA6-related disorders. Here, we describe two new individuals and review the previously published cases. MATERIALS AND METHODS: Clinical investigations were carried out in accordance with local guidelines and clinical information was retrieved from medical records. Genetic studies were carried out using next-generation sequencing based clinical exome sequencing. A PubMed literature search was performed with a review of the published clinical cases of Oliver McFarlane syndrome. RESULTS: Our first individual was a 36-year-old woman with 32 years of follow up and our second individual was a 3-year-old boy. Both individuals were born preterm and presented with prolonged neonatal respiratory distress, trichomegaly, early growth retardation, retinopathy and sparse depigmented hair. So far, none of our cases have demonstrated cognitive impairment or progressive neurological symptoms, but the child revealed persistent abnormal lung structure. Both individuals were compound heterozygous for pathogenic PNPLA6 variants, one of which was novel. We found other 31 clinically documented published cases. CONCLUSIONS: Our two new unrelated cases of Oliver McFarlane Syndrome demonstrate early ophthalmological and systemic findings of this rare syndrome and the progressive nature of the retinopathy with a long follow-up. PNPLA6-related disorders are a phenotypically highly heterogenous group where alterations in the phosphatidylcholine metabolism can lead to manifestations in different tissues with no clear genotype-phenotype correlation.

Gordon Holmes syndrome caused by two novel mutations in the PNPLA6 gene.

Gordon Holmes syndrome (GHS) is an autosomal recessive disease characterized by cerebellar ataxia and hypogonadotropic hypogonadism. Among the genes associated with this syndrome, mutations in PNPLA6 have been detected and correlated with the phenotype of GHS. We report a case of a patient affected with GHS, confirmed by physical, neurological, laboratory and genetic analyses. Two compound heterozygous missense mutations on the PNPLA6 gene described as probably damaging/damaging in multiple in silico predictive tools have been detected with massive multigene sequencing. Interestingly, brain MRI uncovered abnormalities in the periventricular white matter, which so far have not been associated with GHS caused by PNPLA6 mutations.

Drosophila Lysophospholipase Gene swiss cheese Is Required for Survival and Reproduction.

Drosophila melanogaster is one of the most famous insects in biological research. It is widely used to analyse functions of different genes. The phosphatidylcholine lysophospholipase gene swiss cheese was initially shown to be important in the fruit fly nervous system. However, the role of this gene in non-nervous cell types has not been elucidated yet, and the evolutional explanation for the conservation of its function remains elusive. In this study, we analyse expression pattern and some aspects of the role of the swiss cheese gene in the fitness of Drosophila melanogaster. We describe the spatiotemporal expression of swiss cheese throughout the fly development and analyse the survival and productivity of swiss cheese mutants. We found swiss cheese to be expressed in salivary glands, midgut, Malpighian tubes, adipocytes, and male reproductive system. Dysfunction of swiss cheese results in severe pupae and imago lethality and decline of fertility, which is impressive in males. The latter is accompanied with abnormalities of male locomotor activity and courtship behaviour, accumulation of lipid droplets in testis cyst cells and decrease in spermatozoa motility. These results suggest that normal swiss cheese is important for Drosophila melanogaster fitness due to its necessity for both specimen survival and their reproductive success.

Morpho-Functional Consequences of Swiss Cheese Knockdown in Glia of Drosophila melanogaster.

Glia are crucial for the normal development and functioning of the nervous system in many animals. Insects are widely used for studies of glia genetics and physiology. Drosophila melanogaster surface glia (perineurial and subperineurial) form a blood-brain barrier in the central nervous system and blood-nerve barrier in the peripheral nervous system. Under the subperineurial glia layer, in the cortical region of the central nervous system, cortex glia encapsulate neuronal cell bodies, whilst in the peripheral nervous system, wrapping glia ensheath axons of peripheral nerves. Here, we show that the expression of the evolutionarily conserved swiss cheese gene is important in several types of glia. swiss cheese knockdown in subperineurial glia leads to morphological abnormalities of these cells. We found that the number of subperineurial glia nuclei is reduced under swiss cheese knockdown, possibly due to apoptosis. In addition, the downregulation of swiss cheese in wrapping glia causes a loss of its integrity. We reveal transcriptome changes under swiss cheese knockdown in subperineurial glia and in cortex + wrapping glia and show that the downregulation of swiss cheese in these types of glia provokes reactive oxygen species acceleration. These results are accompanied by a decline in animal mobility measured by the negative geotaxis performance assay.

Bi-allelic variants in PNPLA6 possibly associated with Parkinsonian features in addition to spastic paraplegia phenotype.

Variants in the PNPLA6 gene are known to cause 4 distinct phenotypes. One known phenotype is Hereditary Spastic Paraplegia type 39 (HSP 39), a rare neurodegenerative condition characterized by variable onset of lower limb spasticity, weakness and ataxia. Little is known about complications of HSP 39 in adulthood. Here, we report a family of three siblings who presented with bilateral lower limb spasticity in childhood, consistent with HSP, with confirmed bi-allellic PNPLA6 mutations. Two siblings developed parkinsonian features in middle age, a novel finding in this sibship. The proband had a positive dopamine transporter scan, indicating degeneration in dopaminergic neurons, and dopa-responsive extrapyramidal symptoms. Testing for known genetic causes of Parkinsonism was negative. The PNPLA6 gene encodes neuropathy target esterase, an enzyme involved in lipid metabolism that is critical to the stability of cell membranes. We hypothesize that the development of Parkinsonism in these patients may be related to the PNPLA6 mutations, as lipid dysregulation has been implicated in the pathogenesis of Parkinson disease.

Identification of Oliver-McFarlane syndrome caused by novel compound heterozygous variants of PNPLA6.

OBJECTIVES: Oliver-McFarlane syndrome (OMCS) is an autosomal recessive inherited disease resulting from PNPLA6 mutations that results in intellectual impairment and profound short stature. To obtain a better understanding of the genotype-phenotype correlations for PNPLA6-related disorders, we reported the 14th OMCS case and summarized all the reported cases of OMCS. METHODS: We collected clinical biochemical and data and brain MRI data and used whole-exon gene detection and analysis tools to evaluate the pathogenicity of the variants, including PolyPhen-2 and Mutation Taster, and we also generated three-dimensional protein structures and visualized the effects of altered residues with I-TASSER and PyMOL Viewer software. RESULTS: The patient presented with trichomegaly and multiple pituitary hormone deficiencies. Brain MRI showed small pituitary and bilateral paraventricular leukomalacia. Novel variants (c.1491G > T and c.3367G > A) in the PNPLA6 gene were detected in the proband and verified by direct sequencing. Amino acid residues of Gln497 and Gly1123 are predicted to be damaging and destroy the three-dimensional protein structures of the protein. In follow-up, this patient could neither walk nor hold his head erect and had not spoken one word at the age of one year and ten months. Moreover, there is no obvious hot spot mutation in any of the reported allelic variants. Interestingly, the majority of mutations are located in the phospholipid esterase domain, which is responsible for esterase activity. CONCLUSIONS: We identified two novel variants of the PNPLA6 gene in an OMCS patient, which will help to better understand the function of PNPLA6 and genotype-phenotype correlations for PNPLA6-related disorders.