Bi-allelic Variants in the GPI Transamidase Subunit PIGK Cause a Neurodevelopmental Syndrome with Hypotonia, Cerebellar Atrophy, and Epilepsy
AMERICAN JOURNAL OF HUMAN GENETICS
Authors: Thi Tuyet Mai Nguyen; Murakami, Yoshiko; Mobilio, Sabrina; Niceta, Marcello; Zampino, Giuseppe; Philippe, Christophe; Moutton, Sebastien; Zaki, Maha S.; James, Kiely N.; Musaev, Damir; Mu, Weiyi; Baranano, Kristin; Nance, Jessica R.; Rosenfeld, Jill A.; Braverman, Nancy; Ciolfi, Andrea; Millan, Francisca; Person, Richard E.; Bruel, Ange-Line; Thauvin-Robinet, Christel; Ververi, Athina; DeVile, Catherine; Male, Alison; Efthymiou, Stephanie; Maroofian, Reza; Houlden, Henry; Maqbool, Shazia; Rahman, Fatima; Baratang, Nissan, V; Rousseau, Justine; St-Denis, Anik; Elrick, Matthew J.; Anselm, Irina; Rodan, Lance H.; Tartaglia, Marco; Gleeson, Joseph; Kinoshita, Taroh; Campeau, Philippe M.
Abstract
Glycosylphosphatidylinositol (GPI)-anchored proteins are critical for embryogenesis, neurogenesis, and cell signaling. Variants in several genes participating in GPI biosynthesis and processing lead to decreased cell surface presence of GPI-anchored proteins (GPI-APs) and cause inherited GPI deficiency disorders (IGDs). In this report, we describe 12 individuals from nine unrelated families with 10 different bi-allelic PIGK variants. PIGK encodes a component of the GPI transamidase complex, which attaches the GPI anchor to proteins. Clinical features found in most individuals include global developmental delay and/or intellectual disability, hypotonia, cerebellar ataxia, cerebellar atrophy, and facial dysmorphisms. The majority of the individuals have epilepsy. Two individuals have slightly decreased levels of serum alkaline phosphatase, while eight do not. Flow cytometric analysis of blood and fibroblasts from affected individuals showed decreased cell surface presence of GPI-APs. The overexpression of wild-type (WT) PIGK in fibroblasts rescued the levels of cell surface GPI-APs. In a knockout cell line, transfection with WT PIGK also rescued the GPI-AP levels, but transfection with the two tested mutant variants did not. Our study not only expands the clinical and known genetic spectrum of IGDs, but it also expands the genetic differential diagnosis for cerebellar atrophy. Given the fact that cerebellar atrophy is seen in other IGDs, flow cytometry for GPI-APs should be considered in the work-ups of individuals presenting this feature.
Pallidal deep brain stimulation in primary Meige syndrome: clinical outcomes and psychiatric features
JOURNAL OF NEUROLOGY NEUROSURGERY AND PSYCHIATRY
Authors: Hao, Qingpei; Wang, Dongliang; OuYang, Jia; Ding, Hu; Wu, Gaungyong; Liu, Zhi; Liu, Ru'en
Abstract
Objectives To study the efficacy and safety of bilateral globus pallidus internus deep brain stimulation (GPi-DBS) in refractory Meige syndrome (MS) and evaluate the psychiatric disorders before and after surgery. Methods Twenty-two patients with MS treated with bilateral GPi-DBS were retrospectively analysed before surgery and after continuous neurostimulation. Before surgery, patients were assessed by the Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS), Self-Rating Depression Scale, Medical Outcomes Study 36-Item Short-Form General Health Survey (SF-36) and Pittsburgh Sleep Quality Index (PQSI), which corresponded to motor symptoms, depressive state, quality of life and sleep quality, respectively. The implantable pulse generator of each patient was activated at 1 month after surgery. At 1 month, 3 months, 6 months and 12 months after continuous neurostimulation, all patients were evaluated by the same scales above. Results The BFMDRS movement scores decreased from 15.0 +/- 5.3 before surgery to 3.5 +/- 4.5 at 12 months after neurostimulation, with a mean improvement of 78% (p<0.001). The BFMDRS disability scores improved from 7.4 +/- 4.9 before surgery to 4.0 +/- 4.6 at 12 months after neurostimulation, with a mean improvement of 56% (p<0.001). The postoperative SF-36 scores had the remarkable improvement compared with baseline scores. Impaired sleep quality was found in 82% of patients and depression in 64% before surgery, which didn't neither obtained amelioration after continuous neurostimulation. Conclusions Bilateral pallidal neurostimulation is a beneficial therapeutic option for refractory MS, which could improve the motor symptoms except for depression and sleep quality.