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Quantitative susceptibility mapping of deep brain nuclei in 22q11.2 deletion syndrome
(Frontiers Media SA, 2026-01-09)
Nestor Muñoz
;
Marisleydis García
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Analía Cuiza
;
Angeles Tepper
;
Javiera Vásquez
<jats:sec> <jats:title>Background</jats:title> <jats:p>22q11.2 Deletion Syndrome (22q11.2 DS) confers a high risk to dopamine-related disorders such as schizophrenia and Parkinson’s disease. These disorders have recently been associated with abnormal iron concentrations in deep brain nuclei. In this study we hypothesized that abnormal iron concentrations may also appear in deep brain nuclei of individuals with 22q11.2 DS.</jats:p> </jats:sec> <jats:sec> <jats:title>Methods</jats:title> <jats:p>We analyzed iron concentrations in four dopamine-related nuclei (caudate, putamen, substantia nigra, and globus pallidus) of 32 individuals, including adolescents and adults, carriers of the 22q11.2 DS and 49 healthy controls. For all individuals, we characterized iron concentrations in each region by quantifying R2* values and using a recently developed technique called Quantitative Susceptibility Mapping (QSM). We used linear mixed models to analyze potential differences between 22q11.2 DS individuals and our control group, considering brain region, age, sex, laterality, volume size, and framewise-displacement as fixed-effect covariates and individuals’ intercepts as random effects.</jats:p> </jats:sec> <jats:sec> <jats:title>Results</jats:title> <jats:p>All individuals showed age-related increases in R2* values and susceptibility within dopaminergic nuclei (caudate, putamen, and substantia nigra). However, individuals with 22q11.2 DS showed a significantly lower rate of increase compared to healthy control group. This suggests that, over time, individuals with 22q11.2 deletion syndrome accumulate less iron in these nuclei than healthy controls.</jats:p> </jats:sec> <jats:sec> <jats:title>Conclusions</jats:title> <jats:p>Individuals with 22q11.2 DS present lower iron accumulation in dopaminergic areas, such as substantia nigra, caudate and putamen, relative to healthy controls. These findings suggest a possible association between a dopaminergic dysfunction and abnormal iron accumulation.</jats:p> </jats:sec>
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Abnormal nodal and global network organization in resting state functional MRI from subjects with the 22q11 deletion syndrome
(2021)
Teuntje A. D. Pelgrim
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Matthijs G. Bossong
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Analía Cuiza
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Luz María Alliende
;
Carlos Mena
<jats:title>Abstract</jats:title><jats:p>The 22q11 deletion syndrome is a genetic disorder associated with a high risk of developing psychosis, and is therefore considered a neurodevelopmental model for studying the pathogenesis of schizophrenia. Studies have shown that localized abnormal functional brain connectivity is present in 22q11 deletion syndrome like in schizophrenia. However, it is less clear whether these abnormal cortical interactions lead to global or regional network disorganization as seen in schizophrenia. We analyzed from a graph-theory perspective fMRI data from 40 22q11 deletion syndrome patients and 67 healthy controls, and reconstructed functional networks from 105 brain regions. Between-group differences were examined by evaluating edge-wise strength and graph theoretical metrics of local (weighted degree, nodal efficiency, nodal local efficiency) and global topological properties (modularity, local and global efficiency). Connectivity strength was globally reduced in patients, driven by a large network comprising 147 reduced connections. The 22q11 deletion syndrome network presented with abnormal local topological properties, with decreased local efficiency and reductions in weighted degree particularly in hub nodes. We found evidence for abnormal integration but intact segregation of the 22q11 deletion syndrome network. Results suggest that 22q11 deletion syndrome patients present with similar aberrant local network organization as seen in schizophrenia, and this network configuration might represent a vulnerability factor to psychosis.</jats:p>
1Scopus© Citations 2
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Functional Dysconnectivity in Ventral Striatocortical Systems in 22q11.2 Deletion Syndrome
(2021)
Ángeles Tepper
;
Analía Cuiza
;
Luz María Alliende
;
Carlos Mena
;
Juan Pablo Ramirez-Mahaluf
<jats:title>Abstract</jats:title> <jats:p>22q11.2 deletion syndrome (22q11.2DS) is a genetic neurodevelopmental disorder that represents one of the greatest known risk factors for psychosis. Previous studies in psychotic subjects without the deletion have identified a dopaminergic dysfunction in striatal regions, and dysconnectivity of striatocortical systems, as an important mechanism in the emergence of psychosis. Here, we used resting-state functional MRI to examine striatocortical functional connectivity in 22q11.2DS patients. We used a 2 × 2 factorial design including 125 subjects (55 healthy controls, 28 22q11.2DS patients without a history of psychosis, 10 22q11.2DS patients with a history of psychosis, and 32 subjects with a history of psychosis without the deletion), allowing us to identify network effects related to the deletion and to the presence of psychosis. In line with previous results from psychotic patients without 22q11.2DS, we found that there was a dorsal to ventral gradient of hypo- to hyperstriatocortical connectivity related to psychosis across both patient groups. The 22q11.2DS was additionally associated with abnormal functional connectivity in ventral striatocortical networks, with no significant differences identified in the dorsal system. Abnormalities in the ventral striatocortical system observed in these individuals with high genetic risk to psychosis may thus reflect a marker of illness risk.</jats:p>
1Scopus© Citations 6

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