Genetic heterogeneity in familial idiopathic basal ganglia calcification (Fahr disease)

Unveiling distinct clinical manifestations of primary familial brain calcifications in Asian and European patients: A study based on 10-year individual-level data

BACKGROUND

Primary Familial Brain Calcification (PFBC) can manifest clinically with a complex and heterogeneous array of symptoms, including parkinsonism, dysarthria, and cognitive impairment. However, the distinct presentations of PFBC in Asian and European populations remain unclear.

METHODS

We conducted a systematic search of PubMed for studies involving genetically confirmed PFBC patients. Demographic data, genetic information, radiological examinations, and clinical characteristics were extracted for each case.

RESULTS

The study included 120 publications and 564 genetically confirmed PFBC patients. Asian and European PFBC populations represented 54 % and 37 % of global patients, respectively. While calcification patterns showed no significant differences between Asian and European PFBC patients, European autosomal dominant PFBC variant carriers were more likely to exhibit clinical symptoms compared to their Asian counterparts (OR = 2.90, 95 % CI 1.55-5.60) and had an earlier estimated age of onset (median age 42 vs 58).

CONCLUSION

The interaction between regional differences and genetically determined calcification severity may collectively influence PFBC symptom progression. Future research should further explore the potential roles of gene modifiers, ethnic background, socioeconomic and environmental exposure factors underlying regional differences in PFBC progression.

Navigating diagnostic uncertainty in fahr's disease: a case report with neuroimaging correlations

Fahr's disease is a rare neurological disorder which is characterized by the presence of abnormal, symmetrical, and bilateral calcifications within the basal ganglia and other cerebral areas. Seizures are 1 of the symptoms that may aid in its diagnosis. Fahr's disease is diagnosed in adults mostly. In this account, we describe the case of a male in his late 20s who was diagnosed with Fahr's disease. The patient experienced multiple seizures and severe headaches for the past 5 months. His medical history was not significant. Upon his admission to the emergency department, imaging studies (Computed Tomography and Magnetic Resonance Imaging) revealed the presence of bilateral and symmetrical calcifications situated within the bilateral corona radiata, bilateral centrum semiovale, bilateral gangliocapsular region, bilateral thalamus and bilateral dentate nucleus. Laboratory investigations ruled out alternative causes for secondary intracranial calcification. Moreover, the patient had no significant familial history. Considering the clinical, biological, and radiological evaluations, the diagnosis was concluded to align with a sporadic form of Fahr's disease. Although seizures are less common symptoms associated with Fahr's disease, the identification of bilateral and symmetrical calcifications in the basal ganglia and other regions on radiological imaging in a patient presenting with seizures should warrant consideration of this neurologic disorder, following the exclusion of other potential causes of intracranial calcification.

Slc20a1 and Slc20a2 regulate neuronal plasticity and cognition independently of their phosphate transport ability

In recent years, primary familial brain calcification (PFBC), a rare neurological disease characterized by a wide spectrum of cognitive disorders, has been associated to mutations in the sodium (Na)-Phosphate (Pi) co-transporter SLC20A2. However, the functional roles of the Na-Pi co-transporters in the brain remain still largely elusive. Here we show that Slc20a1 (PiT-1) and Slc20a2 (PiT-2) are the most abundant Na-Pi co-transporters expressed in the brain and are involved in the control of hippocampal-dependent learning and memory. We reveal that Slc20a1 and Slc20a2 are differentially distributed in the hippocampus and associated with independent gene clusters, suggesting that they influence cognition by different mechanisms. Accordingly, using a combination of molecular, electrophysiological and behavioral analyses, we show that while PiT-2 favors hippocampal neuronal branching and survival, PiT-1 promotes synaptic plasticity. The latter relies on a likely Otoferlin-dependent regulation of synaptic vesicle trafficking, which impacts the GABAergic system. These results provide the first demonstration that Na-Pi co-transporters play key albeit distinct roles in the hippocampus pertaining to the control of neuronal plasticity and cognition. These findings could provide the foundation for the development of novel effective therapies for PFBC and cognitive disorders.

Fahr's disease with an atypical onset of epileptic seizure

Fahr's disease is a rare neurodegenerative disorder first described by Karl Theodor in 1930, defined by abnormal calcified deposits in the basal ganglia and cerebral cortex. Fahr's disease commonly affects young to middle-aged adults with various clinical presentations, including endocrinologic, dermatologic, and neurologic problems, with extrapyramidal symptoms being the most common manifestation. In this case report, we present a case of an epileptic seizure as the first manifestation of Fahr's disease in a 45-year-old male.

Fahr’s Syndrome Presenting As Pre-senile Dementia With Behavioral Abnormalities: A Rare Case Report

Fahr’s syndrome is a rare neurological disorder characterized by bilateral basal ganglia calcification. Calcification may also involve other brain areas like dentate nuclei of the cerebellum, thalamus, cerebral cortex, hippocampus, and subcortical white matter. Many cases of Fahr’s syndrome present with movement disorders, but may also present with dementia, psychiatric manifestations, and language difficulties. Fahr’s syndrome generally occurs secondary to metabolic abnormality mainly hypoparathyroidism. Fahr’s disease is another variant that is characterized by idiopathic bilateral calcification of basal ganglia in absence of any evident etiology. The present case report presented a rare case of Fahr’s syndrome secondary to hypoparathyroidism presenting with pre-senile dementia with behavioral abnormalities.

Just "one of so many"? The pathologist Theodor Fahr (1877-1945) and his ambivalent relationship to National Socialism

Theodor Fahr is well known as a pioneer in renal pathology and the eponym of "Fahr's disease". While his professional merits are undisputed, his relationship to National Socialism remains unclear. On the one hand, he signed the public "oath of allegiance" of German professors to Adolf Hitler, on the other hand, he appeared as a mentor to his Jewish colleague Paul Kimmelstiel. In 1945, Fahr committed suicide after being dismissed by the Allied military government for political reasons. However, he left behind memoirs in which he outlined himself as a determined opponent of National Socialism. It is precisely these ambiguities that form the starting point of this study. The aim is to reconstruct Fahr's personal and professional career and to outline his political stance in the Third Reich. In addition, it will be clarified how Fahr's life and work were received after 1945 and whether (or how) his relationship to National Socialism was addressed. This study is based on different types of sources: Various archival documents on Fahr and Kimmelstiel are compared and contrasted with Fahr's unpublished autobiography and the available secondary literature on Fahr and his work. The analysis shows that Fahr's relationship to National Socialism became more distanced over time. However, he did not emerge as a critic of Nazi ideology during the Third Reich - even though he claimed in his memoirs that he had consistently despised Hitler. While Fahr is not to be considered an ardent National Socialist, he held to the stereotype of the "unscrupulous" Jew. The study concludes that Fahr was a politically ambivalent character with a distinctly anti-Semitic disposition, which he tried to soften by emphasizing his relationships with individual Jewish colleagues such as Kimmelstiel.

Sepsis Unmasking Fahr's Disease

Fahr's disease is a sporadic or familial neurodegenerative disorder characterized by symmetrical calcification of cerebral structures, particularly the basal ganglia, cerebellar dentate nuclei and surrounding white matter, in the absence of metabolic causes of calcification. We report the case of a previously fit, high functioning 58-year-old man who developed catastrophic irreversible neuropsychiatric collapse after sepsis despite appropriate antimicrobial treatment. Cranial computed tomography revealed extensive diffuse calcifications located in unusual areas. Laboratory studies excluded the presence of other pathologic processes leading to secondary intracranial calcification and a multigene panel failed to confirm mutations in the genes currently known to be associated with the disorder, supporting a diagnosis of sporadic Fahr's disease or idiopathic brain calcification. Important diagnostic considerations in the septic patient who develops neurological complications, namely sepsis-associated encephalopathy and antibiotic-associated encephalopathy, are discussed. The patient remains severely handicapped 6 months after the acute event. Patients with clinically silent neurodegenerative/neuropsychiatric conditions, such as Fahr's disease, may present with florid and unpredicted neurological features in the context of systemic illness.

[Basal ganglia calcification]

Calcifications of the basal ganglia are frequently seen on the cerebral CT scans and particularly in the globus pallidus. Their frequency increases physiologically with age after 50 years old. However, pathological processes can also be associated with calcium deposits in the gray nuclei, posterior fossa or white matter. Unilateral calcification is often related to an acquired origin whereas bilateral ones are mostly linked to an acquired or genetic origin that will be sought after eliminating a perturbation of phosphocalcic metabolism. In pathological contexts, these calcifications may be accompanied by neurological symptoms related to the underlying disease: Parkinson's syndrome, psychiatric and cognitive disorders, epilepsy or headache. The purpose of this article is to provide a diagnostic aid, in addition to clinical and biology, through the analysis of calcification topography and the study of different MRI sequences.

Longitudinal observation of ten family members with idiopathic basal ganglia calcification: A case report

BACKGROUND

Familial idiopathic basal ganglia calcification (FIBGC) is a rare autosomal dominant disorder that causes bilateral calcification of the basal ganglia and/or cerebellar dentate nucleus, among other locations.

CASE SUMMARY

The aim of this study is to report 10 cases of FIBGC observed in a single family. Seven patients showed calcification on their computed tomography scan, and all of these patients carried the SLC20A2 mutation. However, individuals without the mutation did not show calcification. Three patients among the 7 with calcification were symptomatic, while the remaining 4 patients were asymptomatic. Additionally, we longitudinally observed 10 subjects for ten years. In this paper, we mainly focus on the clinical course and neuroradiological findings in the proband and her son.

CONCLUSION

The accumulation of more case reports and further studies related to the manifestation of FIBGC are needed.

Fahr's Disease Presenting with Manic Symptoms

Bilateral striopallidodentate calcinosis, commonly known as Fahr's disease, is a rare syndrome characterised by symmetrical calcification over the basal ganglion and dentate nucleus. No case of Fahr's disease with associated manic symptoms has been described in the literature to date. We report an unusual case of Fahr's Disease in a 18 year old unmarried male who presented to the emergency department of Universal College of Medical Sciences - Teaching Hospital, Nepal with symptoms of mania. Computed tomographic scan of the patient demonstrated extensive symmetrical calcification over the basal ganglia and dentate nuclei. No underlying cause for the bilateral calcification was found. This rare case of Fahr's disease, which has never been reported in Indian literature has been reported to highlight this unusual condition and its differentiation from the commoner Fahr's syndrome.

Primary familial brain calcifications

Primary familial brain calcification (PFBC) is a neurodegenerative disease with characteristic calcium deposits in the basal ganglia and other brain regions. The disease usually presents as a combination of abnormal movements, cognitive and psychiatric manifestations, clinically indistinguishable from other adult-onset neurodegenerative disorders. The differential diagnosis must be established with genetic and nongenetic disorders that can also lead to calcium deposits in encephalic structures. In the past years PFBC causal mutations have been discovered in genes related to calcium phosphate homeostasis (SLC20A2, XPR1) and in genes involved with endothelial function and integrity (PDGFB, PDGFRB). The most frequently mutated gene is SLC20A2, where mutations can affect any domain of the protein. There is no clearcut relationship between the specific mutation/gene, onset age, neuroimaging pattern, and severity of clinical manifestations. The discovery of the genetic basis of PFBC provides not only a diagnostic tool, but also an insight into the pathomechanisms and potential therapeutic trials for this rare disease.

Clinical and radiological diversity in genetically confirmed primary familial brain calcification

Primary familial brain calcification (PFBC) is a rare neuropsychiatric disorder with characteristic symmetrical brain calcifications. Patients with PFBC may have a variety of symptoms, although they also may be clinically asymptomatic. Parkinsonism is one of the most common movement disorders; however, the underlying mechanism remains unclear. This condition is typically transmitted in an autosomal dominant fashion. To date, mutations in SLC20A2, PDGFRB, PDGFB, and XPR1 have been reported to cause PFBC. The aim of the study was to identify the genetic cause of brain calcification in probands from three PFBC families and in 8 sporadic patients and to perform clinical and radiological assessments focusing on parkinsonism in mutation carriers. Three familial PFBC probands and their relatives and eight sporadic patients affected with brain calcifications were enrolled in this study. Whole-exome sequencing identified three novel mutations: c.269G > T, p.(Gly90Val) and c.516+1G > A in SLC20A2 in familial cases, and c.602-1G > T in PDGFB in a sporadic patient. The c.516+1G > A mutation resulted in exon 4 skipping in SLC20A2 (p.Val144Glyfs*85). Dopamine transporter single photon emission computed tomography using ¹²³I-ioflupane and ¹²³I-metaiodobenzylguanidine cardiac scintigraphy revealed pre-synaptic dopaminergic deficit and cardiac sympathetic nerve dysfunction in two SLC20A2-related PFBC patients with parkinsonism.

Fahr Syndrome - an Important Piece of a Puzzle in the Differential Diagnosis of Many Diseases

Fahr syndrome is a rare neurodegenerative disorder characterized by symmetrical, bilateral calcifications in the basal ganglia, nucleus gyrus and cerebral cortex. The continuous advancement as well as widespread use of brain imaging have contributed to the increasing detection rates of such changes. Nevertheless, their etiology is understood only partially and the methods of causative treatment are limited. Due to various symptoms, Fahr syndrome may resemble diseases from the field of neurology, psychiatry, cardiology and even urology. This article provides an up-to-date review of the literature concerning Fahr syndrome in terms of clinical practice.

Elimination of huntingtin in the adult mouse leads to progressive behavioral deficits, bilateral thalamic calcification, and altered brain iron homeostasis

Huntington's Disease (HD) is an autosomal dominant progressive neurodegenerative disorder characterized by cognitive, behavioral and motor dysfunctions. HD is caused by a CAG repeat expansion in exon 1 of the HD gene that is translated into an expanded polyglutamine tract in the encoded protein, huntingtin (HTT). While the most significant neuropathology of HD occurs in the striatum, other brain regions are also affected and play an important role in HD pathology. To date there is no cure for HD, and recently strategies aiming at silencing HTT expression have been initiated as possible therapeutics for HD. However, the essential functions of HTT in the adult brain are currently unknown and hence the consequence of sustained suppression of HTT expression is unpredictable and can potentially be deleterious. Using the Cre-loxP system of recombination, we conditionally inactivated the mouse HD gene homologue at 3, 6 and 9 months of age. Here we show that elimination of Htt expression in the adult mouse results in behavioral deficits, progressive neuropathological changes including bilateral thalamic calcification, and altered brain iron homeostasis.

Novel mutations of PDGFRB cause primary familial brain calcification in Chinese families

Four causative genes, including solute carrier family 20 member 2 (SLC20A2), platelet-derived growth factor receptor b (PDGFRB), platelet-derived growth factor b (PDGFB)and xenotropic and polytropic retrovirus receptor 1 (XPR1), have been identified to cause primary familial brain calcification (PFBC). However, PDGFRB mutations seem to be quite rare and no PDGFRB mutations have been reported in Chinese PFBC patients. A total of 146 PFBC patients including 12 families and 134 sporadic patients were recruited in this study. All of them were previously tested negative for the SLC20A2. Mutational analyses of the entire exons and exon-intron boundaries of PDGFRB were carried out by direct gene sequencing. In silico analyses of the identified variants were conducted using Mutation Taster, PolyPhen-2 and Sorts Intolerant From Tolerant. Two heterozygous variants, c.3G>A and c.2209G>A, of the PDGFRB gene were revealed in two PFBC families, respectively. These two variants were not observed in 200 healthy controls. The variant c.3G>A was located in exon 2 and affected the initiation codon of the PDGFRB gene. The variant c.2209G>A resulted in amino-acid substitutions of aspartic acid to asparagine at position 737. Both of these two variants co-segregated with the disease phenotype (variant carriers in Family 1: I1, II2 and II3; variant carriers in Family 2: I2 and II8), suggesting a pathogenic impact of these variants. The prevalence of PDGFRB mutations in Chinese PFBC patients seems to be quite low, indicating that PDGFRB is not a major causative gene of PFBC in Chinese population.

Deconstructing Fahr's disease/syndrome of brain calcification in the era of new genes

INTRODUCTION

There are now a number genes, known to be associated with familial primary brain calcification (PFBC), causing the so called 'Fahr's' disease or syndrome. These are SCL20A2, PDGFB, PDGFRB and XPR1. In this systematic review, we analyse the clinical and radiological features reported in genetically confirmed cases with PFBC. We have additionally reviewed pseudohypoparathyroidism which is a close differential diagnosis of PFBC in clinical presentation and is also genetically determined.

METHODS

We performed a Medline search, from 1st Jan 2012 through to 7th November 2016, for publications with confirmed mutations of SCL20A2, PDGFB, PDGFRB, and XPR1 and found twenty papers with 137 eligible cases. A second search was done for publications of cases with Pseudohypoparathyroidism or pseudopseudohypoparathyroidism, and found 18 publications with 20 eligible cases.

RESULTS

SLC20A2 was the most common gene involved with 75 out of 137 cases included with PFBC (55%) followed by PDGFB (31%) and PDGFRB (11%). Statistically significant correlation was found between the presence of parkinsonism with SLC20A2 mutations, headache in PDGFB and generalised tonic-clonic seizures in patients with pseudohypoparathyroidism.

CONCLUSION

We combine statistical analysis and clinical inference to suggest a diagnostic algorithm based on the observations in this study to help with investigation of a patient with neurological features and brain calcification.

Fahr's syndrome presenting with epileptic seizure: Two case reports

Fahr’s syndrome is a neuropsychiatric syndrome characterized by symmetrical and bilateral intracerebral calcifications located in the basal ganglia and usually associated with a phosphorus and calcium metabolism disorder. Clinical manifestations of Fahr’s syndrome vary; it may start at different ages and have a variety of presentations. This article discusses rare presentation of Fahr’s syndrome with epileptic seizure. These cases are important because they appear to be the first cases in the literature of Fahr’s syndrome presenting with generalized tonic clonic seizure.

Nomenclature of genetic movement disorders: Recommendations of the international Parkinson and movement disorder society task force

The system of assigning locus symbols to specify chromosomal regions that are associated with a familial disorder has a number of problems when used as a reference list of genetically determined disorders,including (I) erroneously assigned loci, (II) duplicated loci, (III) missing symbols or loci, (IV) unconfirmed loci and genes, (V) a combination of causative genes and risk factor genes in the same list, and (VI) discordance between phenotype and list assignment. In this article, we report on the recommendations of the International Parkinson and Movement Disorder Society Task Force for Nomenclature of Genetic Movement Disorders and present a system for naming genetically determined movement disorders that addresses these problems. We demonstrate how the system would be applied to currently known genetically determined parkinsonism, dystonia, dominantly inherited ataxia, spastic paraparesis, chorea, paroxysmal movement disorders, neurodegeneration with brain iron accumulation, and primary familial brain calcifications. This system provides a resource for clinicians and researchers that, unlike the previous system, can be considered an accurate and criterion-based list of confirmed genetically determined movement disorders at the time it was last updated.

Idiopathic basal ganglia calcification presenting as schizophrenia-like psychosis and obsessive-compulsive symptoms: A case report

Idiopathic basal ganglia calcification (IBGC) is a rare neurodegenerative disorder characterized by the deposition of calcium in the brain and variable combinations of movement disorders, gait impairment and neuropsychiatric symptoms. Few reports have described psychiatric manifestations as early symptoms of IBGC. The present study reports the case of a middle-aged man with schizophrenia-like psychosis and obsessive-compulsive symptoms as the first manifestations of IBGC. The response of the patient to olanzapine and fluoxetine suggests that low-dose olanzapine is effective and should be increased cautiously to avoid worsening parkinsonism and that fluoxetine is an effective drug for the treatment of obsessive-compulsive symptoms in IBGC.

Fahr's disease: a rare neurological presentation in a tropical setting

While rare, Fahr's disease should be considered as a differential diagnosis for seizures, movement disorders, or cognitive impairment in tropical settings. Classically, bilateral calcification of the basal ganglia is seen on CT. Endemic infections, metabolic, and toxic causes should be excluded. Treatment using Levodopa is often beneficial.

Generalized epilepsy in a family with basal ganglia calcifications and mutations in SLC20A2 and CHRNB2

BACKGROUND

The genetic understanding of primary familial brain calcification (PFBC) has increased considerably in recent years due to the finding of causal genes like SLC20A2, PDGFRB and PDGFB. The phenotype of PFBC is complex and has as of yet been poorly delineated. The most common clinical presentations include movement disorders, cognitive symptoms and psychiatric conditions. We report a family including two sisters with brain calcifications due to a variant in SLC20A2 and generalized tonic-clonic seizures as the principal phenotypic trait.

METHODS

The affected siblings underwent whole exome sequencing and candidate variants and cosegregation in the family were validated by Sanger sequencing.

RESULTS

Both siblings and their asymptomatic father were heterozygous for a variant in SLC20A2. The siblings also had a variant in CHRNB2, a known epilepsy gene associated with autosomal dominant frontal lobe epilepsy, which they had inherited from the mother.

CONCLUSIONS

To our knowledge, the reported siblings represent the third and fourth subjects with confirmed SLC20A2 variants exhibiting epilepsy as a phenotypic trait. Our findings support seizures as part of the phenotypic spectrum of SLC20A2-related PFBC. However, the present phenotype may also result from additional genetic influence, such as the identified missense variant in CHRNB2.

Idiopathic Basal Ganglia Calcification Presented with Impulse Control Disorder

Primary familial brain calcification (PFBC), also referred to as Idiopathic Basal Ganglia Calcification (IBGC) or “Fahr's disease,” is a clinical condition characterized by symmetric and bilateral calcification of globus pallidus and also basal ganglions, cerebellar nuclei, and other deep cortical structures. It could be accompanied by parathyroid disorder and other metabolic disturbances. The clinical features are dysfunction of the calcified anatomic localization. IBGC most commonly presents with mental damage, convulsion, parkinson-like clinical picture, and neuropsychiatric behavior disorders; however, presentation with impulse control disorder is not a frequent presentation. In the current report, a 43-year-old male patient who has been admitted to psychiatry policlinic with the complaints of aggressive behavior episodes and who has been diagnosed with impulse control disorder and IBGC was evaluated in the light of the literature.

Mutations in XPR1 cause primary familial brain calcification associated with altered phosphate export

Primary familial brain calcification (PFBC) is a neurological disease characterized by calcium phosphate deposits in the basal ganglia and other brain regions and has thus far been associated with SLC20A2, PDGFB or PDGFRB mutations. We identified in multiple families with PFBC mutations in XPR1, a gene encoding a retroviral receptor with phosphate export function. These mutations alter phosphate export, implicating XPR1 and phosphate homeostasis in PFBC.

The genetics of primary familial brain calcifications

Bilateral accumulation of calcium in the brain, most commonly in the basal ganglia, but also in the cerebellum, thalamus, and brainstem can be inherited in an autosomal dominant fashion and is then referred to as primary familial brain calcifications (PFBC). Clinical manifestations include a spectrum of movement disorders and neuropsychiatric abnormalities. In the past 2 years, 3 genes have been identified to cause PFBC, (ie, SLC20A2, PDGFRB, and PDGFB). SCL20A2 encodes the Type III sodium-dependent inorganic phosphate (Pi) transporter 2 (PiT2) and, when mutated, uptake of Pi is severely impaired likely causing buildup of calcium phosphate. The second identified cause of PFBC is mutations in PDGFRB, which codes for platelet-derived growth factor receptor β (PDGF-Rβ). Interestingly, the third PFBC gene is PDGFB that encodes the ligand of PDGF-Rβ, which is secreted during angiogenesis to recruit pericytes, thereby implying impairment of the blood-brain barrier as a disease mechanism of PFBC.

Fahr's disease in two siblings in a family: A case report

Idiopathic basal ganglia calcification, also known as Fahr's disease, is a rare neurological disease characterized by basal ganglia calcification, Parkinsonism and psychiatric symptoms. The majority of patients with Fahr's disease are adults. The present study describes the cases of two patients with Fahr's disease. The patients were brother and sister and their parents were close relatives. The onset age of Fahr's disease in these two patients was early, with the onset age of the brother being in the teens and the sister in early childhood. The patients exhibited different clinical manifestations. The main symptoms of the male patient were Parkinson's disease appearance and the loss of the ability to carry out simple calculations, while the main symptoms of the female patient were grand mal seizures and cerebellar ataxia. Although the two patients had distinct clinical manifestations, they both had similar intracranial multiple calcifications. The computed tomography scan remains the main method used in the diagnosis of Fahr's disease. Following treatment with dopamine and a dopamine receptor agonist, the extra-pyramidal symptoms of the male were significantly relieved. The female patient was administered antiepileptic drugs and there was no recurrence of epilepsy following treatment.

Primary familial brain calcification: update on molecular genetics

Primary familial brain calcification is a neuropsychiatric disorder with calcium deposits in the brain, especially in basal ganglia, cerebellum and subcortical white matter. The disease is characterized by a clinical heterogeneity, with a various combination of symptoms that include movement disorders and psychiatric disturbances; asymptomatic patients have been also reported. To date, three causative genes have been found: SLC20A2, PDGFRB and PDGFB. SLC20A2 gene codes for the 'sodium-dependent phosphate transporter 2' (PiT-2), a cell membrane transporters of inorganic phosphate, involved in Pi uptake by cells and maintenance of Pi body levels. Over 40 pathogenic variants of SLC20A2 have been reported, affecting the regulation of Pi homeostasis. It was hypothesized that SLC20A2 mutations cause brain calcification most likely through haploinsufficiency. PDGFRB encodes for the platelet-derived growth factor receptor-β (PDGFRβ), a cell-surface tyrosine-kinase (RTK) receptor that regulates cell proliferation, migration, survival and differentiation. PDGFB encodes for the 'platelet-derived growth factor beta' (PDGFβ), the ligand of PDGFRβ. The loss of function of PDGFRβ and PDGFβ could lead to the impairment of the pericytes function and blood brain barrier integrity, causing vascular and perivascular calcium accumulation. SLC20A2 accounts for about 40 % of familial form and 14 % of sporadic cases, while PDGFRB and PDGFB mutations are likely rare. However, approximately 50 % of patients are not genetically defined and there should be at least another causative gene.

First Japanese family with primary familial brain calcification due to a mutation in the PDGFB gene: an exome analysis study

AIMS

Primary familial brain calcification (PFBC) is a rare disorder characterized by abnormal deposits of calcium in the basal ganglia and cerebellum. PFBC can present with a spectrum of neuropsychiatric symptoms resembling those seen in dementia and schizophrenia. Mutations in a few genes have been identified as causing PFBC: namely, the SLC20A2 gene that codes for the sodium-dependent phosphate transporter and the PDGFRB gene that codes for the platelet-derived growth factor receptor β (PDGF-Rβ). A recent study identified mutations in PDGFB coding for PDGF-B, the main ligand for PDGF-Rβ, in six families with PFBC. Here we report the first Japanese family with PFBC carrying a mutation in PDGFB, which causes the substitution of an arginine with a stop codon at amino acid 149 of the PDGF-B protein (p. Arg149*).

METHODS

Clinical histories and computed tomography scan images were provided. Sanger sequencing was performed for the exome analysis of SLC20A2 and PDGFB genes.

RESULTS

One family member began to complain of auditory hallucination at 16 years of age and had been treated for schizophrenia. His father suffered from memory and gait disturbances in his late 60s. A computed tomography scan revealed a symmetrical area of calcification over the basal ganglia in both cases. A known mutation in PDGFB (c.445C>T, p.Arg149*) was consistently detected in both PFBC cases by Sanger sequencing. No mutations in SLC20A2 were detected.

CONCLUSIONS

Our findings suggest that this mutation in PDGF-B is responsible for PFBC in this Japanese family and that abnormal PDGF signaling may be involved in the pathophysiology of certain psychiatric disorders.

Novel overgrowth syndrome phenotype due to recurrent de novo PDGFRB mutation

Using exome analysis, we identified a novel overgrowth syndrome arising from a mutation in PDGFRB, which plays a critical role in growth and differentiation. This entity is characterized by somatic overgrowth, distinctive facial features, hyperelastic and fragile skin, white matter lesions, and neurologic deterioration.

[The causative gene of Parkinsonism and its medical treatment strategy]

Parkinsonism is a neurological syndrome characterized by tremor, hypokinesia, rigidity, and postural instability. The neurodegenerative condition of Parkinson's disease (PD) is the most common cause of parkinsonism. PD is classified as sporadic PD and familial PD. Whereas idiopathic PD is caused by a number of complex factors, familial PD is a result of mutations in PD-associated genes. Unraveling the mechanisms surrounding familial PD will offer pivotal clues in understanding etiology of not only familial PD but also sporadic PD. We have demonstrated neuroprotective effects with particular focus on DJ-1. On the other hand, idiopathic basal ganglia calcification, also known as Fahr disease (FD) is another condition characterized by parkinsonism. In 2012, solute carrier family 20A2 (SLC20A2) was identified as the causative gene for familial FD. Our analysis of patient samples revealed a novel mutation in SLC20A2. Type-III sodium-dependent phosphate transporter 2 (PiT-2), the protein encoded by SLC20A2, plays an important role in phosphate homeostasis. However, PiT-2's role in the pathology of FD remains largely unclear. We have established induced pluripotent stem (iPS) cells from FD patients and are investigating their usefulness in drug development. Here, we present some of our latest research findings.

Primary familial brain calcification: Genetic analysis and clinical spectrum

BACKGROUND

Primary familial brain calcification (PFBC) is a rare autosomal dominant disorder with bilateral calcification of basal ganglia and other cerebral regions, movement disorders, and neuropsychiatric disturbances. So far, three causative genes have been discovered: SLC20A2, PDGFRB and PDGFB, accounting for approximately 50% of cases.

METHODS

Seven unrelated families with primary brain calcification were recruited to undergo clinical and genetic analysis, including Sanger sequencing of SLC20A2, PDGFRB, and PDGFB, and copy number analysis of SLC20A2.

RESULTS

Mutations in SLC20A2 have been detected in three families: p.Glu368Glyfs*46, p.Ser434Trp, and p.Thr595Met. Intrafamilial phenotype variability has been observed. In spite of this, we found similar neuroimaging pattern among members of the same family.

CONCLUSIONS

This molecular analysis expands the mutational spectrum of SLC20A2, which remains the major causative gene of primary familial brain calcification, and suggests the existence of disease-causing mutations in at least another, still unknown gene.

Congenital and acquired disorders presenting as psychosis in children and young adults

A review of the published literature found 60 congenital and acquired disorders with symptoms that include psychosis in youth. The prevalence, workup, genetics, and associated neuropsychiatric features of each disorder are described. Eighteen disorders (30%) have distinct phenotypes (doorway diagnoses); 18 disorders (30%) are associated with intellectual disability; and 43 disorders (72%) have prominent neurologic signs. Thirty-one disorders (52%) can present without such distinct characteristics, and are thus more easily overlooked. A systematic and cost-effective differential diagnostic approach based on estimated prevalence and most prominent associated signs is recommended.

Phenotypic spectrum of probable and genetically-confirmed idiopathic basal ganglia calcification

Idiopathic basal ganglia calcification is characterized by mineral deposits in the brain, an autosomal dominant pattern of inheritance in most cases and genetic heterogeneity. The first causal genes, SLC20A2 and PDGFRB, have recently been reported. Diagnosing idiopathic basal ganglia calcification necessitates the exclusion of other causes, including calcification related to normal ageing, for which no normative data exist. Our objectives were to diagnose accurately and then describe the clinical and radiological characteristics of idiopathic basal ganglia calcification. First, calcifications were evaluated using a visual rating scale on the computerized tomography scans of 600 consecutively hospitalized unselected controls. We determined an age-specific threshold in these control computerized tomography scans as the value of the 99th percentile of the total calcification score within three age categories: <40, 40-60, and >60 years. To study the phenotype of the disease, patients with basal ganglia calcification were recruited from several medical centres. Calcifications that rated below the age-specific threshold using the same scale were excluded, as were patients with differential diagnoses of idiopathic basal ganglia calcification, after an extensive aetiological assessment. Sanger sequencing of SLC20A2 and PDGFRB was performed. In total, 72 patients were diagnosed with idiopathic basal ganglia calcification, 25 of whom bore a mutation in either SLC20A2 (two families, four sporadic cases) or PDGFRB (one family, two sporadic cases). Five mutations were novel. Seventy-one per cent of the patients with idiopathic basal ganglia calcification were symptomatic (mean age of clinical onset: 39 ± 20 years; mean age at last evaluation: 55 ± 19 years). Among them, the most frequent signs were: cognitive impairment (58.8%), psychiatric symptoms (56.9%) and movement disorders (54.9%). Few clinical differences appeared between SLC20A2 and PDGFRB mutation carriers. Radiological analysis revealed that the total calcification scores correlated positively with age in controls and patients, but increased more rapidly with age in patients. The expected total calcification score was greater in SLC20A2 than PDGFRB mutation carriers, beyond the effect of the age alone. No patient with a PDGFRB mutation exhibited a cortical or a vermis calcification. The total calcification score was more severe in symptomatic versus asymptomatic individuals. We provide the first phenotypical description of a case series of patients with idiopathic basal ganglia calcification since the identification of the first causative genes. Clinical and radiological diversity is confirmed, whatever the genetic status. Quantification of calcification is correlated with the symptomatic status, but the location and the severity of the calcifications don't reflect the whole clinical diversity. Other biomarkers may be helpful in better predicting clinical expression.

Fahr's disease: bilateral symmetrical striopallidodentate calcification in two brothers with two distinct presentations

Bilateral striopallidodentate calcinosis, commonly known as Fahr's disease is a rare clinical entity present mainly with extrapyramidal signs and accompanied with metabolic, biochemical, neuroradiological and neuropsychiatric situations. It is characterised by the symmetrical and bilateral intracranial deposition of calcium associated with cell loss in the basal ganglia, cerebral cortex and cerebellum.In this study, we discussed two brothers' cases of Fahr's diseases who presented with different symptomatology. The first presented with walking difficulty, cramps and dysarthria and moderate memory impairment whereas the second with vertigo, ataxia, forgetfulness and headache. CT scans of both patients revealed intracranial diffuse bilateral calcifications in the basal ganglia and the cerebellum. The second patient revealed progressive cerebral atrophy but reduction in the calcification. Fahr's disease, although encountered rarely, should also be taken into account in the differential diagnosis of cases with abnormal intracranial calcifications along with other familial, congenital and metabolic diseases and syndromes.

Novel SLC20A2 mutations identified in southern Chinese patients with idiopathic basal ganglia calcification

Idiopathic basal ganglia calcification (IBGC) is a rare neuropsychiatric disorder characterized by bilateral and symmetric cerebral calcifications. Recently, SLC20A2 was identified as a causative gene for familial IBGC, and three mutations were reported in a northern Chinese population. Here, we aimed to explore the mutation spectrum of SLC20A2 in a southern Chinese population. Sanger sequencing was employed to screen mutations within SLC20A2 in two IBGC families and 14 sporadic IBGC cases from a southern Han Chinese population. Four novel mutations (c.82G>A p.D28N, c.185T>C p.L62P, c.1470_1478delGCAGGTCCT p.Q491_L493del and c.935-1G>A) were identified in two families and two sporadic cases, respectively; none were detected in 200 unrelated controls. No mutation was found in the remaining 12 patients. Different mutations may result in varied phenotypes, including brain calcification and clinical manifestations. Our study supports the hypothesis that SLC20A2 is a causative gene of IBGC and expands the mutation spectrum of SLC20A2, which facilitates the understanding of the genotype-phenotype correlation of IBGC.

Basal ganglia calcification as a putative cause for cognitive decline

Basal ganglia calcifications (BGC) may be present in various medical conditions, such as infections, metabolic, psychiatric and neurological diseases, associated with different etiologies and clinical outcomes, including parkinsonism, psychosis, mood swings and dementia. A literature review was performed highlighting the main neuropsychological findings of BGC, with particular attention to clinical reports of cognitive decline. Neuroimaging studies combined with neuropsychological analysis show that some patients have shown progressive disturbances of selective attention, declarative memory and verbal perseveration. Therefore, the calcification process might represent a putative cause for dementia syndromes, suggesting a probable link among calcinosis, the aging process and eventually with neuronal death. The increasing number of reports available will foster a necessary discussion about cerebral calcinosis and its role in determining symptomatology in dementia patients

Association between a novel mutation in SLC20A2 and familial idiopathic basal ganglia calcification

Familial idiopathic basal ganglia calcification (FIBGC) is a rare, autosomal dominant disorder involving bilateral calcification of the basal ganglia. To identify gene mutations related to a Chinese FIBGC lineage, we evaluated available individuals in the family using CT scans. DNA was extracted from the peripheral blood of available family members, and both exonic and flanking intronic sequences of the SLC20A2 gene were amplified by PCR and then sequenced. Non-denaturing polyacrylamide gel electrophoresis (PAGE) was used to confirm the presence of mutations. Allele imbalances of the SLC20A2 gene or relative quantity of SLC20A2 transcripts were evaluated using qRT-PCR. A novel heterozygous single base-pair deletion (c.510delA) within the SLC20A2 gene was identified. This deletion mutation was found to co-segregate with basal ganglia calcification in all of the affected family members but was not detected in unaffected individuals or in 167 unrelated Han Chinese controls. The mutation will cause a frameshift, producing a truncated SLC20A2 protein with a premature termination codon, most likely leading to the complete loss of function of the SLC20A2 protein. This mutation may also lead to a reduction in SLC20A2 mRNA expression by approximately 30% in cells from affected individuals. In conclusion, we identified a novel mutation in SLC20A2 that is linked to FIBGC. In addition to the loss of function at the protein level, decreasing the expression of SLC20A2 mRNA may be another mechanism that can regulate SLC20A2 function in IBGC individuals. We propose that the regional expression pattern of SLC20A1 and SLC20A2 might explain the unique calcification pattern observed in FIBGC patients.

Mutations in SLC20A2 are a major cause of familial idiopathic basal ganglia calcification

Familial idiopathic basal ganglia calcification (IBGC) or Fahr's disease is a rare neurodegenerative disorder characterized by calcium deposits in the basal ganglia and other brain regions, which is associated with neuropsychiatric and motor symptoms. Familial IBGC is genetically heterogeneous and typically transmitted in an autosomal dominant fashion. We performed a mutational analysis of SLC20A2, the first gene found to cause IBGC, to assess its genetic contribution to familial IBGC. We recruited 218 subjects from 29 IBGC-affected families of varied ancestry and collected medical history, neurological exam, and head CT scans to characterize each patient's disease status. We screened our patient cohort for mutations in SLC20A2. Twelve novel (nonsense, deletions, missense, and splice site) potentially pathogenic variants, one synonymous variant, and one previously reported mutation were identified in 13 families. Variants predicted to be deleterious cosegregated with disease in five families. Three families showed nonsegregation with clinical disease of such variants, but retrospective review of clinical and neuroimaging data strongly suggested previous misclassification. Overall, mutations in SLC20A2 account for as many as 41% of our familial IBGC cases. Our screen in a large series expands the catalog of SLC20A2 mutations identified to date and demonstrates that mutations in SLC20A2 are a major cause of familial IBGC. Non-perfect segregation patterns of predicted deleterious variants highlight the challenges of phenotypic assessment in this condition with highly variable clinical presentation.

Decreased bioelements content in the hair of patients with Fahr's disease (idiopathic bilateral calcification in the brain)

The remarkable calcification of the basal ganglia and cerebellum has been traditionally called Fahr's disease, but this nomenclature is criticized for including heterogeneous diseases. To determine the pattern of some biological metals in the hair of patients with Fahr's disease, we investigated the levels of 24 bioelements in the hair of 28 patients (17 males and 11 females) with Fahr's disease and compared them with those of three age-, sex-, and living region-matched controls (84 controls in total). Interestingly, we found decreases in the levels of several bioelements [calcium (Ca), copper (Cu), iron (Fe), mercury (Hg), iodine (I), nickel (Ni), phosphate (P), lead (Pb), and selenium (Se)] in the hair of patients. This is in contrast to our previous finding of increases of Cu, Fe, zinc (Zn), and magnesium (Mg) in the cerebrospinal fluid (CSF) of patients. The decreased level of Cu in the hair was the most prominent and pathognomonic, while the increased level of Cu in the CSF had been found to be the most significant in patients. More significant correlations between two bioelements in the hair were recognized in patients than controls. Although Fahr's disease has been considered to be a heterogenous entity, the significant tendencies of several bioelements in the hair of patients in this study suggest metabolic disorders of bioelements, especially biometals, on the background. Some transporters, especially P transporter such as PiT2, of bioelements will be involved in the different distribution of bioelements in the body of patients.

The genetics of dystonias

Dystonia has been defined as a syndrome of involuntary, sustained muscle contractions affecting one or more sites of the body, frequently causing twisting and repetitive movements or abnormal postures. Dystonia is also a clinical sign that can be the presenting or prominent manifestation of many neurodegenerative and neurometabolic disorders. Etiological categories include primary dystonia, secondary dystonia, heredodegenerative diseases with dystonia, and dystonia plus. Primary dystonia includes syndromes in which dystonia is the sole phenotypic manifestation with the exception that tremor can be present as well. Most primary dystonia begins in adults, and approximately 10% of probands report one or more affected family members. Many cases of childhood- and adolescent-onset dystonia are due to mutations in TOR1A and THAP1. Mutations in THAP1 and CIZ1 have been associated with sporadic and familial adult-onset dystonia. Although significant recent progress had been made in defining the genetic basis for most of the dystonia-plus and heredodegenerative diseases with dystonia, a major gap remains in understanding the genetic etiologies for most cases of adult-onset primary dystonia. Common themes in the cellular biology of dystonia include G1/S cell cycle control, monoaminergic neurotransmission, mitochondrial dysfunction, and the neuronal stress response.

Analysis of the CTAGE5 P521A variation with the risk of familial idiopathic basal ganglia calcification in an Iranian population

Familial idiopathic basal ganglia calcification (IBGC) is a rare neurodegenerative syndrome with an autosomal dominant pattern of inheritance which is characterized by deposition of calcium in the basal ganglia and other brain regions. Linkage studies demonstrated its genetic heterogeneity; however, the responsible genes are unknown. Recently, a heterozygous variation (C>G, P521A) at exon 20 of the human cutaneous T cell lymphoma-associated antigen 5 (CTAGE5) gene was found in all patients of the affected large American family linked to IBGC1 (14q11.2-21.3). However, no carrier was detected in the two affected Brazilian families. This study was performed to investigate whether the CTAGE5 P521A variation is associated with the IBGC in an affected Iranian family. Genotyping of the CTAGE5 P521A variation was determined using PCR-RFLP. Totally, 22 members of an affected Iranian family as well as 100 normal people as control group were screened. All the samples including 22 members of the affected family as well as all control people had normal CC genotype and no GC carrier was found. Our result is similar to a Brazilian study but contrary to an American report, strengthening genetic heterogeneity of this syndrome. It seems that additional studies are necessary to confirm the pathogenicity of this rare mutation.

Mutations in SLC20A2 link familial idiopathic basal ganglia calcification with phosphate homeostasis

Familial idiopathic basal ganglia calcification (IBGC) is a genetic condition with a wide spectrum of neuropsychiatric symptoms, including parkinsonism and dementia. Here, we identified mutations in SLC20A2, encoding the type III sodium-dependent phosphate transporter 2 (PiT2), in IBGC-affected families of varied ancestry, and we observed significantly impaired phosphate transport activity for all assayed PiT2 mutants in Xenopus laevis oocytes. Our results implicate altered phosphate homeostasis in the etiology of IBGC.

Metabolic and neurologic sequelae in a patient with long-standing anorexia nervosa who presented with septic shock and deep hypoglycemia

OBJECTIVE

To report the case of a 48-year female with chronic remitting anorexia nervosa who was found comatose at home and admitted to our hospital with a deep hypoglycemia (glucose level 0.6 mmol/L; 11 mg/dL) and septic shock secondary to a bilateral pneumonia.

METHOD

Case report.

RESULTS

After admission to the critical care unit, she further displayed a number of pronounced complications known to be associated with anorexia, including hypophosphatemia, disturbed liver functions and depression of all three hematological cell lines. The neurological recovery of the patient was complicated by encephalopathy and transient tetraparesis. With initial deep hypoglycemia at presentation and persisting coma, magnetic resonance imaging performed 5 days later did not demonstrate characteristic post-hypoglycemic abnormalities. Neuroradiological examination did however reveal the presence of extensive calcifications in the basal ganglia known as Fahr's syndrome.

DISCUSSION

The potential relation between anorexia nervosa and Fahr syndrome has not been described before. The fact that this patient survived a glucose level that is usually associated with a very poor outcome is probably related to its special origin.

Differential diagnosis of chorea

Chorea is a common movement disorder that can be caused by a large variety of structural, neurochemical (including pharmacologic), or metabolic disturbances to basal ganglia function, indicating the vulnerability of this brain region. The diagnosis is rarely indicated by the simple phenotypic appearance of chorea, and can be challenging, with many patients remaining undiagnosed. Clues to diagnosis may be found in the patient's family or medical history, on neurologic examination, or upon laboratory testing and neuroimaging. Increasingly, advances in genetic medicine are identifying new disorders and expanding the phenotype of recognized conditions. Although most therapies at present are supportive, correct diagnosis is essential for appropriate genetic counseling, and ultimately, for future molecular therapies.

Strio-pallido-dentate calcinosis: a diagnostic approach in adult patients

Familial idiopathic bilateral strio-pallido-dentate calcinosis is a rare autosomal dominant disorder characterized by massive symmetric calcification, detectable by CT, into the globus pallidus and striatum, with or without the involvement of the dentate nucleus, thalamus and white matter in the absence of alterations of calcium metabolism. Clinically, it has been associated with movement and/or neuropsychiatric disorders with age at onset typically in the fourth or fifth decade. Other sporadic or familial diseases can be responsible for brain calcifications with a similar anatomic strio-pallidal or strio-pallido-dentate pattern and, a restricted number of them, for neurological symptoms with onset in adulthood. Moreover, physiological age-related basal ganglia calcifications are often incidentally found, although with a far different CT aspect, in elderly patients with movement disorders. Indentifying familial and idiopathic cases may offer the opportunity to study the molecular mechanisms underlying this minerals deposition.

Identification of a novel genetic locus on chromosome 8p21.1-q11.23 for idiopathic basal ganglia calcification

Idiopathic basal ganglia calcification (IBGC) is a neurodegenerative disorder that is characterized by basal ganglia and extrabasal ganglia calcification, and usually inherited in an autosomal dominant pattern. To date, two genetic loci for IBGC were identified on chromosomes 14q and 2q, but further genetic heterogeneity clearly exists. In this study, a large Chinese family with autosomal dominant IBGC was characterized. Linkage analysis excluded the 14q13 and 2q37 loci. The large family was then characterized by genome-wide linkage analysis to identify a novel genetic locus for IBGC. Significant linkage was identified with markers on chromosome 8p21.1-q11.23 with a maximum LOD score of 4.10. Fine mapping defined the new genetic locus within a 25 Mb region between markers D8S1809 and D8S1833. Future studies of the candidate genes at the 8p21.1-q11.23 locus may lead to identification of a disease-causing gene with IBGC.