The Pathology of Primary Familial Brain Calcification: Implications for Treatment / 神经科学通报·英文版

Primary familial brain calcification (PFBC) is an inherited neurodegenerative disorder mainly characterized by progressive calcium deposition bilaterally in the brain, accompanied by various symptoms, such as dystonia, ataxia, parkinsonism, dementia, depression, headaches, and epilepsy. Currently, the etiology of PFBC is largely unknown, and no specific prevention or treatment is available. During the past 10 years, six causative genes (SLC20A2, PDGFRB, PDGFB, XPR1, MYORG, and JAM2) have been identified in PFBC. In this review, considering mechanistic studies of these genes at the cellular level and in animals, we summarize the pathogenesis and potential preventive and therapeutic strategies for PFBC patients. Our systematic analysis suggests a classification for PFBC genetic etiology based on several characteristics, provides a summary of the known composition of brain calcification, and identifies some potential therapeutic targets for PFBC.

Mechanisms of PiT2-loop7 Missense Mutations Induced Pi Dyshomeostasis / 神经科学通报·英文版

PiT2 is an inorganic phosphate (Pi) transporter whose mutations are linked to primary familial brain calcification (PFBC). PiT2 mainly consists of two ProDom (PD) domains and a large intracellular loop region (loop7). The PD domains are crucial for the Pi transport, but the role of PiT2-loop7 remains unclear. In PFBC patients, mutations in PiT2-loop7 are mainly nonsense or frameshift mutations that probably cause PFBC due to C-PD1131 deletion. To date, six missense mutations have been identified in PiT2-loop7; however, the mechanisms by which these mutations cause PFBC are poorly understood. Here, we found that the p.T390A and p.S434W mutations in PiT2-loop7 decreased the Pi transport activity and cell surface levels of PiT2. Furthermore, we showed that these two mutations attenuated its membrane localization by affecting adenosine monophosphate-activated protein kinase (AMPK)- or protein kinase B (AKT)-mediated PiT2 phosphorylation. In contrast, the p.S121C and p.S601W mutations in the PD domains did not affect PiT2 phosphorylation but rather impaired its substrate-binding abilities. These results suggested that missense mutations in PiT2-loop7 can cause Pi dyshomeostasis by affecting the phosphorylation-regulated cell-surface localization of PiT2. This study helps understand the pathogenesis of PFBC caused by PiT2-loop7 missense mutations and indicates that increasing the phosphorylation levels of PiT2-loop7 could be a promising strategy for developing PFBC therapies.

A family study of autosomal recessive primary familial brain calcification caused by JAM2 gene mutation and literature review / 中华神经科杂志

Objective:To improve the clinician′s recognition of the clinical and molecular characteristics of primary familial brain calcification (PFBC).Methods:The detailed clinical information, imaging and molecular characteristics were analyzed in proband and family members of a genetically confirmed autosomal recessive PFBC family. The clinical and imaging features of junctional adhesion molecule 2 (JAM2) gene related PFBC were analyzed in combination with the literature review.Results:The proband was a 32-year-old man, with slurred speech and paroxysmal limb twitch as the first symptoms, accompanied by cognitive dysfunction, and rigidity in the limbs, with epilepsy in the past. Brain CT showed extensive, symmetrical, and bilateral calcification involving the cerebellum, basal ganglia, thalamus, subcortex and cortex. Other family members showed no related clinical symptoms. Brain CT of the parents of the proband showed no calcification. Gene testing of the proband revealed a homozygous c.685C>T(p.R229*) mutation in JAM2 gene, which has been reported as a pathogenic variation abroad, whereas has not been reported in China. The proband′s parents and children were found with heterozygous c.685C>T (p.R229*) mutation.Conclusions:Autosomal recessive inherited PFBC is a rare disease, and JAM2 mutation is a newly discovered pathogenic gene of PFBC in 2020. Patients with intracranial calcification should be alert of JAM2 gene mutation.

Clinical research study of Familial Idiopathic Basal Ganglia Calcification from 8 family analysis / 中国神经精神疾病杂志

Objective To better understand the clinical characteristics of Familial Idiopathic Basal Ganglia Calcifi?cation (FIBGC), including at the perspective of hereditary pattern, clinical test results, onset age, clinical heterogeneity and the volume of basal ganglia calcification (VBGC). Method 8 Eight FIBGC families were collected and draw family pedigrees were draw. Analysis of was conducted on the patient's clinical test results, head CT and MRI changes, onset ag?es, relationship of clinical manifestations with VBGC. Results No significant difference was found in serum calcium, alu?minum, arsenic, cobalt, magnesium, phosphorus, iron, parathyroid hormone and calcitonin concentration between the fam?ily members of patients and healthy controls (P>0.05). Family members from 8 FIBGC families including the two with consanguineous marriage manifested autosomal dominant heredity. The severity of , symptomatic s was correlated with VBGCpatients showed the same clinical manifestations in the dyskinesia family. The psychiatric symptoms was not asso? ciated with VBGC whereas patients with dyskinesia had a large VBGC. There was a significant difference in onset age be?tween patients with psychiatric symptoms and those with dyskinesia. P.atients with dyskinesia suffer larger VBGC, and is characterized by Patients with dyskinesia had relatively later onset age (43.95 ± 2.47 y) whereas those with. psychiatric symptoms hadsymptomatic patients with early onset age (31.32±10.16y). The comparison of the onset age (43.954±2.473 vs. 31.319±10.156 y, t=4.438, P=0.001) and VBGC (1.748±0.622 vs. 0.392±0.276 cm3, t=2.518, P=0.028) with symptom?atic patients between dyskinesia and psychogenic families was significant. Conclusions Eight FIBGC families manifested autosomal dominant heredity. Patients with dyskinesia suffer have a larger VBGC and are associated with a, and is char?acterized by relatively later onset age. In contrast, patients with psychiatric symptomspsychogeny is not related withhave a the small VBGC and showedand their age of onset is young. earlier onset age.

A Study on MR Signal Intensity of Calcifications According to Calcium Concentration and Compound

PURPOSE: The signal of intracranial calcification on magnetic resonance (MR) imaging has been known to bevariable. The purpose of this study was to evaluate the MR signal of calcifications according to calciumconcentration and compound. MATERIALS AND METHODS: T1-weighted, proton density and T2-weighted images were obtained in phantoms with various conposition of calcium carbonate and calcium phosphate. The signal intensities and T1/T2 relaxation times were measured and analyzed according to calcium concentration and compound. The configurations of calcium particles were evaluated by scanning electron microscopy. RESULTS: The signal intensity of calcium carbonate on T1-weighted images gradually decreased as the concentration increased, while that ofcalcium phosphate showed a biphasic curve with a peak intensity at 0.2 g/ml. The signal intensity of both calcium compounds on T2-weighted images decreased as the concentration increased. The T1 relaxation time of calcium carbonate remained constant with increasing calcium concentration, however, that of calcium phosphate decreased upto 0.2g/ml and then remained constant. The T2 relaxation time of both calcium compounds decreased in a similar fashion with increasing concentration. Calcium phosphate showed larger surface area on scanning electron microscope. CONCLUSION: Calcifications show variable MR signal due to difference of T1 and T2 relaxation times according to calcium concentration and compound. Large surface area of calcium particle might cause shortening of T1 relaxation time leading to high signal on T1-weighted image. Understanding of these findings will help interpretation of MR images more precisely.

Multiple Brain Calcification in Chronic Lead Poisoning / 예방의학회지

We experienced a case of occupational lead poisoning employed in a secondary lead smelting plant for 12 years. The patient was 39-year-old male and had been felt dizziness, recent memory impairment and intermittent severe abdominal pain for 2 years. On admission, blood lead level was 92.9 microgram/dl, urinary lead level was 19,9 microgram/l and zinc protoporphyrin level was 226.0 microgram/dl. On the blood test, hemoglobin was 10.6 g/dl and showed normocytic normochromic anemia. There were no abnormal findings in the biochemical and hormonal tests. Decrease of I.Q. and use of words in speaking were found in the psychiatric and psychologic examinations. We observed the finding of motor polyneuropathy in the nerve conduction velocity test. Computed tomographic finding showed calcification lesions in the basal ganglia, dentate nuclei, caudate nuclei, and especially characteristic multiple calcifications were located in the subcortical white matter.