Brain morphological analysis in PTEN hamartoma tumor syndrome

Exome sequencing identifies protein-coding variants associated with loneliness and social isolation

BACKGROUND

Loneliness and social isolation are serious yet underappreciated public health problems, with their genetic underpinnings remaining largely unknown. We aimed to explore the role of protein-coding variants in the manifestation of loneliness and social isolation.

METHODS

We conducted the first exome-wide association analysis on loneliness and social isolation, utilizing 336,115 participants of white-British ancestry for loneliness and 346,115 for social isolation. Sensitivity analyses were performed to validate the genetic findings. We estimated the genetic burden heritability of loneliness and social isolation and provided biological insights into them.

RESULTS

We identified six novel risk genes (ANKRD12, RIPOR2, PTEN, ARL8B, NF1, and PIMREG) associated with loneliness and two (EDARADD and GIGYF1) with social isolation through analysis of rare coding variants. Brain-wide association analysis uncovered 47 associations between identified genes and brain structure phenotypes, many of which are critical for social processing and interaction. Phenome-wide association analysis established significant links between these genes and phenotypes across five categories, mostly blood biomarkers and cognitive measures.

LIMITATIONS

The measurements of loneliness and social isolation in UK Biobank are brief for these multi-layer social factors, some relevant aspects may be missed.

CONCLUSIONS

Our study revealed 13 risk genes associated with loneliness and 6 with social isolation, with the majority being novel discoveries. These findings advance our understanding of the genetic basis of these two traits. The study provides a foundation for future studies aimed at exploring the functional mechanisms of these genes and their potential implications for public health interventions targeting loneliness and social isolation.

PTEN mutations impair CSF dynamics and cortical networks by dysregulating periventricular neural progenitors

Enlargement of the cerebrospinal fluid (CSF)-filled brain ventricles (ventriculomegaly) is a defining feature of congenital hydrocephalus (CH) and an under-recognized concomitant of autism. Here, we show that de novo mutations in the autism risk gene PTEN are among the most frequent monogenic causes of CH and primary ventriculomegaly. Mouse Pten-mutant ventriculomegaly results from aqueductal stenosis due to hyperproliferation of periventricular Nkx2.1+ neural progenitor cells (NPCs) and increased CSF production from hyperplastic choroid plexus. Pten-mutant ventriculomegalic cortices exhibit network dysfunction from increased activity of Nkx2.1+ NPC-derived inhibitory interneurons. Raptor deletion or postnatal everolimus treatment corrects ventriculomegaly, rescues cortical deficits and increases survival by antagonizing mTORC1-dependent Nkx2.1+ NPC pathology. Thus, PTEN mutations concurrently alter CSF dynamics and cortical networks by dysregulating Nkx2.1+ NPCs. These results implicate a nonsurgical treatment for CH, demonstrate a genetic association of ventriculomegaly and ASD, and help explain neurodevelopmental phenotypes refractory to CSF shunting in select individuals with CH.

Using cortical organoids to understand the pathogenesis of malformations of cortical development

Malformations of cortical development encompass a broad range of disorders associated with abnormalities in corticogenesis. Widespread abnormalities in neuronal formation or migration can lead to small head size or microcephaly with disorganized placement of cell types. Specific, localized malformations are termed focal cortical dysplasias (FCD). Neurodevelopmental disorders are common in all types of malformations of cortical development with the most prominent being refractory epilepsy, behavioral disorders such as autism spectrum disorder (ASD), and learning disorders. Several genetic pathways have been associated with these disorders from control of cell cycle and cytoskeletal dynamics in global malformations to variants in growth factor signaling pathways, especially those interacting with the mechanistic target of rapamycin (mTOR), in FCDs. Despite advances in understanding these disorders, the underlying developmental pathways that lead to lesion formation and mechanisms through which defects in cortical development cause specific neurological symptoms often remains unclear. One limitation is the difficulty in modeling these disorders, as animal models frequently do not faithfully mirror the human phenotype. To circumvent this obstacle, many investigators have turned to three-dimensional human stem cell models of the brain, known as organoids, because they recapitulate early neurodevelopmental processes. High throughput analysis of these organoids presents a promising opportunity to model pathophysiological processes across the breadth of malformations of cortical development. In this review, we highlight advances in understanding the pathophysiology of brain malformations using organoid models.

Clinical Neurologic Features and Evaluation of PTEN Hamartoma Tumor Syndrome: A Systematic Review

BACKGROUND AND OBJECTIVES

PTEN hamartoma tumor syndrome (PHTS) is a well-recognized hereditary tumor syndrome and is now also recognized as a common cause of monogenic autism spectrum disorder. There is a vast spectrum of phenotypic variability across individuals with PHTS, and in addition to neurodevelopmental challenges, patients with PHTS may experience a wide variety of neurologic challenges, many of which have only recently been described. Thus, this systematic review aimed to summarize the breadth of the current knowledge of neurologic conditions in individuals with PHTS.

METHODS

We conducted a systematic review using the MEDLINE and EMBASE databases until January 2023. We included studies that reported neurologic signs, symptoms, and diagnoses in patients with a diagnosis of PHTS. Two independent reviewers extracted data (neurologic diagnoses and patient details) from each study. Case reports, case series, prospective studies, and therapeutic trials were included. We assessed the quality of evidence using the appropriate tool from the JBI, depending on study design.

RESULTS

One thousand nine hundred ninety-six articles were screened, and 90 articles met the inclusion criteria. The majority of the included studies were case reports (49/90, 54%) or small case series (31/90, 34%). Epilepsy secondary to cerebral malformations, neurologic deficits from spinal or cranial arteriovenous malformations, and rare tumors such as dysplastic cerebellar gangliocytoma are among the more severe neurologic features reported across patients with PHTS. One interventional randomized control trial examining neurocognitive endpoints was identified and did not meet its efficacy endpoint.

DISCUSSION

Our systematic review defines a broad scope of neurologic comorbidities occurring in individuals with PHTS. Neurologic findings can be categorized by age at onset in individuals with PTHS. Our study highlights the need for additional clinical trial endpoints, informed by the neurologic challenges faced by individuals with PHTS.

Neuropsychological functioning of adults with PTEN hamartoma tumor syndrome

PTEN hamartoma tumor syndrome (PHTS) might be associated with a distinct cognitive and psychological profile. However, previous studies are limited, predominantly based on small and pediatric cohorts, likely affected by selection bias, and show a broad range of findings. We aimed to characterize the neuropsychological functioning of adults with PHTS. A total of 40 participants, with intellectual disability as exclusion criterium, completed an extensive clinical neuropsychological assessment including cognitive tasks, questionnaires, and a clinical diagnostic interview. The cognitive tasks and questionnaire data were categorized as below and above average based on 1.5 SD. About 80% of participants showed an average level of intelligence. In addition, 30% and 24% of participants scored below average on immediate memory recall and speed of information processing, respectively. Furthermore, about 25% reported above average scores on the majority of the questionnaires, indicating psychological distress, signs of alexithymia, and cognitive complaints. Personality of participants was characterized by inflexibility, social withdrawal, and difficulties in recognizing and describing their own emotions. Adults with PHTS demonstrate a heterogeneous yet distinct neuropsychological profile that is characterized by slower information processing, psychological problems, and specific personality traits. These findings provide directions on how to optimize the care and daily lives of adults with PHTS.

Brain morphometric changes in children born as small for gestational age without catch up growth

Introduction

Most infants born as small for gestational age (SGA) demonstrate catch up growth by 2-4 years, but some fail to do so. This failure is associated with several health risks, including neuropsychological development issues. However, data on the morphological characteristics of the brains of infants born as SGA without achieving catch up growth are lacking. This study aims to determine the structural aspects of the brains of children born as SGA without catch up growth.

Methods

We conducted voxel- and surface-based morphometric analyses of 1.5-T T1-weighted brain images scanned from eight infants born as SGA who could not achieve catch up growth by 3 years and sixteen individuals with idiopathic short stature (ISS) to exclude body size effects. Growth hormone (GH) secretion stimulation tests were used to rule out GH deficiency in all SGA and ISS cases. The magnetic resonance imaging data were assessed using Levene's test for equality of variances and a two-tailed unpaired t-test for equality of means. The Benjamini-Hochberg procedure was used to apply discovery rate correction for multiple comparisons.

Results

Morphometric analyses of both t-statical map and surface-based analyses using general linear multiple analysis determined decreased left insula thickness and volume in SGA without catch up growth compared with ISS.

Conclusion

The brain scans of patients with SGA who lack catch up growth indicated distinct morphological disparities when compared to those with ISS. The discernible features of brain morphology observed in patients born as SGA without catch up growth may improve understanding of the association of SGA without catch up growth with both intellectual and psychological outcomes.

MYCN in human development and diseases

Somatic mutations in MYCN have been identified across various tumors, playing pivotal roles in tumorigenesis, tumor progression, and unfavorable prognoses. Despite its established notoriety as an oncogenic driver, there is a growing interest in exploring the involvement of MYCN in human development. While MYCN variants have traditionally been associated with Feingold syndrome type 1, recent discoveries highlight gain-of-function variants, specifically p.(Thr58Met) and p.(Pro60Leu), as the cause for megalencephaly-polydactyly syndrome. The elucidation of cellular and murine analytical data from both loss-of-function (Feingold syndrome model) and gain-of-function models (megalencephaly-polydactyly syndrome model) is significantly contributing to a comprehensive understanding of the physiological role of MYCN in human development and pathogenesis. This review discusses the MYCN's functional implications for human development by reviewing the clinical characteristics of these distinct syndromes, Feingold syndrome, and megalencephaly-polydactyly syndrome, providing valuable insights into the understanding of pathophysiological backgrounds of other syndromes associated with the MYCN pathway and the overall comprehension of MYCN's role in human development.

Exploring the neurological features of individuals with germline PTEN variants: A multicenter study

OBJECTIVE

PTEN, a known tumor suppressor gene, is a mediator of neurodevelopment. Individuals with germline pathogenic variants in the PTEN gene, molecularly defined as PTEN hamartoma tumor syndrome (PHTS), experience a variety of neurological and neuropsychiatric challenges during childhood, including autism spectrum disorder (ASD). However, the frequency and nature of seizures and the utilization of allied health services have not been described.

METHODS

Young patients with PHTS and sibling controls were recruited across five centers in the United States and followed every 6-12 months for a mean of 2.1 years. In addition to the history obtained from caregivers, neurodevelopmental evaluations and structured dysmorphology examinations were conducted, and brain MRI findings, received therapies, and epilepsy characteristics were reported.

RESULTS

One hundred and seven patients with PHTS (median age 8.7 years; range 3-21 years) and 38 controls were enrolled. ASD and epilepsy were frequent among patients with PHTS (51% and 15%, respectively), with generalized epilepsy strongly associated with ASD. Patients with epilepsy often required two antiseizure medications. Neuroimaging revealed prominent perivascular spaces and decreased peritrigonal myelination in individuals with PHTS-ASD. Allied therapy use was frequent and involved physical, occupational, speech, and social skills therapies, with 89% of all patients with PHTS, regardless of ASD diagnosis, utilizing at least one service.

INTERPRETATION

This prospective, longitudinal study highlights the wide neurological spectrum seen in young individuals with PHTS. ASD is common in PHTS, comorbid with epilepsy, and allied health services are used universally. Our findings inform care discussions with families about neurological outcomes in PHTS.

Variants in PTEN Are Associated With a Diverse Spectrum of Cortical Dysplasia

BACKGROUND

Inactivating mutations in PTEN are among the most common causes of megalencephaly. Activating mutations in other nodes of the PI3K/AKT/MTOR signaling pathway are recognized as a frequent cause of cortical brain malformations. Only recently has PTEN been associated with cortical malformations, and analyses of their prognostic significance have been limited.

METHODS

Retrospective neuroimaging analysis and detailed chart review were conducted on 20 participants identified with pathogenic or likely pathogenic mutations in PTEN and a cortical brain malformation present on brain magnetic resonance imaging.

RESULTS

Neuroimaging analysis revealed four main cerebral phenotypes-hemimegalencephaly, focal cortical dysplasia, polymicrogyria (PMG), and a less severe category, termed "macrocephaly with complicated gyral pattern" (MCG). Although a high proportion of participants (90%) had neurodevelopmental findings on presentation, outcomes varied and were favorable in over half of participants. Consistent with prior work, 39% of participants had autism spectrum disorder and 19% of participants with either pure-PMG or pure-MCG phenotypes had epilepsy. Megalencephaly and systemic overgrowth were common, but other systemic features of PTEN-hamartoma tumor syndrome were absent in over one-third of participants.

CONCLUSIONS

A spectrum of cortical dysplasias is present in individuals with inactivating mutations in PTEN. Future studies are needed to clarify the prognostic significance of each cerebral phenotype, but overall, we conclude that despite a high burden of neurodevelopmental disease, long-term outcomes may be favorable. Germline testing for PTEN mutations should be considered in cases of megalencephaly and cortical brain malformations even in the absence of other findings, including cognitive impairment.

Brain structure alterations in girls with central precocious puberty

Purpose

Central precocious puberty (CPP) is puberty that occurs at an unusually early age with several negative psychological outcomes. There is a paucity of data on the morphological characteristics of the brain in CPP. This study aimed to determine the structural differences in the brain of patients with CPP.

Methods

We performed voxel- and surface-based morphometric analyses of 1.5 T T1-weighted brain images scanned from 15 girls with CPP and 13 age-matched non-CPP controls (NC). All patients with CPP were diagnosed by gonadotropin-releasing hormone (GnRH) stimulation test. The magnetic resonance imaging (MRI) data were evaluated using Levene's test for equality of variances and a two-tailed unpaired t-test for equality of means. False discovery rate correction for multiple comparisons was applied using the Benjamini-Hochberg procedure.

Results

Morphometric analyses of the brain scans identified 33 candidate measurements. Subsequently, increased thickness of the right precuneus was identified in the patients with CPP using general linear models and visualizations of cortical thickness with a t-statistical map and a random field theory map.

Conclusion

The brain scans of the patients with CPP showed specific morphological differences to those of the control. The features of brain morphology in CPP identified in this study could contribute to further understanding the association between CPP and detrimental psychological outcomes.

A randomized controlled trial of Everolimus for neurocognitive symptoms in PTEN hamartoma tumor syndrome

BACKGROUND

PTEN hamartoma tumor syndrome (PHTS) is a complex neurodevelopmental disorder characterized by mTOR (mechanistic target of rapamycin) overactivity. Limited data suggest that mTOR inhibitors may be therapeutic. No placebo-controlled studies have examined mTOR inhibition on cognition and behavior in humans with PHTS with/without autism.

METHODS

We conducted a 6-month phase II, randomized, double-blinded, placebo-controlled trial to examine the safety profile and efficacy of everolimus (4.5 mg/m2) in individuals (5-45 years) with PHTS. We measured several cognitive and behavioral outcomes, and electroencephalography (EEG) biomarkers. The primary endpoint was a neurocognitive composite derived from Stanford Binet-5 (SB-5) nonverbal working memory score, SB-5 verbal working memory, Conners' Continuous Performance Test hit reaction time, and Purdue Pegboard Test score.

RESULTS

Forty-six participants underwent 1:1 randomization: n = 24 (everolimus) and n = 22 (placebo). Gastrointestinal adverse events were more common in the everolimus group (p < 0.001). Changes in the primary endpoint between groups from baseline to month 6 were not apparent (Cohen's d = -0.10, p = 0.518). However, several measures were associated with modest effect sizes (≥0.2) in the direction of improvement, including measures of nonverbal IQ, verbal learning, autism symptoms, motor skills, adaptive behavior, and global improvement. There was a significant difference in EEG central alpha power (p = 0.049) and central beta power (p = 0.039) six months after everolimus treatment.

CONCLUSIONS

Everolimus is well tolerated in PHTS; adverse events were similar to previous reports. The primary efficacy endpoint did not reveal improvement. Several secondary efficacy endpoints moved in the direction of improvement. EEG measurements indicate target engagement following 6 months of daily oral everolimus. Trial Registration Information: ClinicalTrials.gov NCT02991807 Classification of Evidence: I.

Small Nucleus Accumbens and Large Cerebral Ventricles in Infants and Toddlers Prior to Receiving Diagnoses of Autism Spectrum Disorder

Early interventions for autism spectrum disorder (ASD) are increasingly available, while only 42-50% of ASD children are diagnosed before 3 years old (YO). To identify neuroimaging biomarkers for early ASD diagnosis, we evaluated surface- and voxel-based brain morphometry in participants under 3YO who were later diagnosed with ASD. Magnetic resonance imaging data were retrospectively obtained from patients later diagnosed with ASD at Boston Children's Hospital. The ASD participants with comorbidities such as congenital disorder, epilepsy, and global developmental delay/intellectual disability were excluded from statistical analyses. Eighty-five structural brain magnetic resonance imaging images were collected from 81 participants under 3YO and compared with 45 images from 45 gender- and age-matched nonautistic controls (non-ASD). Using an Infant FreeSurfer pipeline, 236 regionally distributed measurements were extracted from each scan. By t-tests and linear mixed models, the smaller nucleus accumbens and larger bilateral lateral, third, and fourth ventricles were identified in the ASD group. Vertex-wise t-statistical maps showed decreased thickness in the caudal anterior cingulate cortex and increased thickness in the right medial orbitofrontal cortex in ASD. The smaller bilateral accumbens nuclei and larger cerebral ventricles were independent of age, gender, or gestational age at birth, suggesting that there are MRI-based biomarkers in prospective ASD patients before they receive the diagnosis and that the volume of the nucleus accumbens and cerebral ventricles can be key MRI-based early biomarkers to predict the emergence of ASD.

Fetal Megalencephaly with Cortical Dysplasia at 18 Gestational Weeks Related to Paternal UPD Mosaicism with PTEN Mutation

The phosphatase and tensin homolog (PTEN) gene is a tumor-suppressor gene located on 10q22-23. Since the introduction of molecular genetics in prenatal diagnostics, various birth defects associated with gene mutations have been diagnosed. However, no reports on fetal cases related to PTEN mutation have been found, so far. We encountered a rare case of fetal PTEN mutation. Fetal macrocephaly was noted at 16 weeks. At 18 and 20 weeks, neurosonography revealed megalencephaly with an asymmetrical structure and multifocal polygyria. The head circumference (HC) was +6.2 SD at 18 weeks and +8.1 SD at 20 weeks. The parents opted for pregnancy termination, and the male fetus was delivered at 21 weeks, with HC +9.3 SD. Single-nucleotide polymorphism (SNP) array for amniotic cells showed paternal uniparental disomy (UPD) 10q mosaicism, and the mosaic ratio was calculated as 56% from B-allele frequency. Exome sequencing revealed the pathogenic PTEN mutation with mosaicism. The heterozygous PTEN mutation may not cause early manifestations from the fetal period, and an abnormal phenotype may appear after birth. This may be the reason why fetal defects associated with PTEN mutation are not detected. Since this case had homozygous and heterozygous mutations, survival was possible, exhibiting an incredibly huge head with cortical dysplasia from early pregnancy.

Quantitative analyses of high-angular resolution diffusion imaging (HARDI)-derived long association fibers in children with sensorineural hearing loss

Sensorineural hearing loss (SNHL) is the most common developmental sensory disorder due to a loss of function within the inner ear or its connections to the brain. While successful intervention for auditory deprivation with hearing amplification and cochlear implants during a sensitive early developmental period can improve spoken-language outcomes, SNHL patients can suffer several cognitive dysfunctions including executive function deficits, visual cognitive impairment, and abnormal visual dominance in speaking perception even after successful intervention. To evaluate whether long association fibers are involved in the pathogenesis of impairment on the extra-auditory cognitive process in SNHL participants, we quantitatively analyzed high-angular resolution diffusion imaging (HARDI) tractography-derived fibers in participants with SNHL. After excluding cases with congenital disorders, perinatal brain damage, or premature birth, we enrolled 17 participants with SNHL aged under 10 years old. Callosal pathways (CP) and six types of cortico-cortical association fibers (arcuate fasciculus [AF], inferior longitudinal fasciculus [ILF], inferior fronto-occipital fasciculus [IFOF], uncinate fasciculus [UF], cingulum fasciculus [CF], and fornix [Fx]) in both hemispheres were identified and visualized. The ILF and IFOF were partly undetected in three profound SNHL participants. Compared to age- and gender-matched neurotypical controls (NC), decreased volumes, increased lengths, and high apparent diffusion coefficient (ADC) values without difference in fractional anisotropy (FA) values were identified in multiple types of fibers in the SNHL group. The impairment of long association fibers in SNHL may partly be related to the association of cognitive dysfunction with SNHL.

Polymicrogyria is Associated With Pathogenic Variants in PTEN

OBJECTIVE

Congenital structural brain malformations have been described in patients with pathogenic phosphatase and tensin homologue (PTEN) variants, but the frequency of cortical malformations in patients with PTEN variants and their impact on clinical phenotype are not well understood. Our goal was to systematically characterize brain malformations in patients with PTEN variants and assess the relevance of their brain malformations to clinical presentation.

METHODS

We systematically searched a local radiology database for patients with PTEN variants who had available brain magnetic resonance imaging (MRI). The MRI scans were reviewed systematically for cortical abnormalities. We reviewed electroencephalogram (EEG) data and evaluated the electronic medical record for evidence of epilepsy and developmental delay.

RESULTS

In total, we identified 22 patients with PTEN pathogenic variants for which brain MRIs were available (age range 0.4-17 years). Twelve among these 22 patients (54%) had polymicrogyria (PMG). Variants associated with PMG or atypical gyration encoded regions of the phosphatase or C2 domains of PTEN. Interestingly, epilepsy was present in only 2 of the 12 patients with PMG. We found a trend toward higher rates of global developmental delay (GDD), intellectual disability (ID), and motor delay in individuals with cortical abnormalities, although cohort size limited statistical significance.

INTERPRETATION

Malformations of cortical development, PMG in particular, represent an under-recognized phenotype associated with PTEN pathogenic variants and may have an association with cognitive and motor delays. Epilepsy was infrequent compared to the previously reported high risk of epilepsy in patients with PMG. ANN NEUROL 2020;88:1153-1164.

Cerebral MRI and Clinical Findings in Children with PTEN Hamartoma Tumor Syndrome: Can Cerebral MRI Scan Help to Establish an Earlier Diagnosis of PHTS in Children?

Background: PTEN Hamartoma Tumor Syndrome (PHTS) is caused by germline autosomal-dominant mutations of the tumor suppressor gene PTEN. Subjects harbour an increased risk for tumor development, with thyroid carcinoma occurring in young children. Establishing a diagnosis is challenging, since not all children fulfill diagnostic criteria established for adults. Macrocephaly is a common feature in childhood, with cerebral MRI being part of its diagnostic workup. We asked whether distinct cMRI features might facilitate an earlier diagnosis. Methods: We retrospectively studied radiological and clinical data of pediatric patients who were presented in our hospital between 2013 and 2019 in whom PTEN gene mutations were identified. Results: We included 27 pediatric patients (18 male) in the analysis. All patients were macrocephalic. Of these, 19 patients had received at least one cMRI scan. In 18 subjects variations were detected: enlarged perivascular spaces (EPVS; in 18), white matter abnormalities (in seven) and less frequently additional pathologies. Intellectual ability was variable. Most patients exhibited developmental delay in motor skills, but normal intelligence. Conclusion: cMRI elucidates EPVS and white matter abnormalities in a high prevalence in children with PHTS and might therefore aid as a diagnostic feature to establish an earlier diagnosis of PHTS in childhood.