Background
Very few longitudinal psychiatric and psychosocial outcome studies of children with mild intellectual disability (MID) have been performed.
Methods
The study group was population based and ...consisted of 82 individuals, born in 1979–1985 and diagnosed in childhood at ages between 3 and 15 years with MID. In the present study, register data regarding school attendance, employment, economic situation, psychiatric diagnoses and criminal sentences were retrieved for the years 1997–2018, when the individuals were up to 39 years old.
Results
At follow‐up, data were obtained for 78 of the 82 individuals (47 male and 31 female). Mean age at follow‐up was 36 years. Of the 78 individuals, 57 (73%) had exclusively received education for pupils with MID, but 21 (27%) had graduated from regular education of some sort (at least 9 years). Forty‐four (56%) had never been employed, and 34 (44%) had been registered as employed for at least a shorter period. Forty‐seven (60%) had received a sick pension at some point in adulthood. Of the 78 individuals, 44 (56%) had any psychiatric disorder recorded and about half of these (n = 21) had had inpatient treatment. A total of 31 of the 44 individuals in psychiatric care (70%) had ID noted as one of their diagnoses. Of the 78 individuals, 48 (62%) had support from the Act concerning Support and Service for Persons with Certain Functional Impairments (Swedish LSS law) as adults. Twenty‐one individuals (27%) had had a criminal conviction, of whom five male individuals had been incarcerated.
Conclusions
Individuals with MID constitute a heterogeneous group with regard to severity of functional impairment, co‐occurring psychiatric disorders and need of support from society. Primary health care, psychiatry and habilitation services need to work together in order to meet the multiple needs of this group.
Intellectual disability (ID) is a measurable phenotypic consequence of genetic and environmental factors. In this study, we prospectively assessed the diagnostic yield of genomic tools (molecular ...karyotyping, multi-gene panel and exome sequencing) in a cohort of 337 ID subjects as a first-tier test and compared it with a standard clinical evaluation performed in parallel. Standard clinical evaluation suggested a diagnosis in 16% of cases (54/337) but only 70% of these (38/54) were subsequently confirmed. On the other hand, the genomic approach revealed a likely diagnosis in 58% (n=196). These included copy number variants in 14% (n=54, 15% are novel), and point mutations revealed by multi-gene panel and exome sequencing in the remaining 43% (1% were found to have Fragile-X). The identified point mutations were mostly recessive (n=117, 81%), consistent with the high consanguinity of the study cohort, but also X-linked (n=8, 6%) and de novo dominant (n=19, 13%). When applied directly on all cases with negative molecular karyotyping, the diagnostic yield of exome sequencing was 60% (77/129). Exome sequencing also identified likely pathogenic variants in three novel candidate genes (DENND5A, NEMF and DNHD1) each of which harbored independent homozygous mutations in patients with overlapping phenotypes. In addition, exome sequencing revealed de novo and recessive variants in 32 genes (MAMDC2, TUBAL3, CPNE6, KLHL24, USP2, PIP5K1A, UBE4A, TP53TG5, ATOH1, C16ORF90, SLC39A14, TRERF1, RGL1, CDH11, SYDE2, HIRA, FEZF2, PROCA1, PIANP, PLK2, QRFPR, AP3B2, NUDT2, UFC1, BTN3A2, TADA1, ARFGEF3, FAM160B1, ZMYM5, SLC45A1, ARHGAP33 and CAPS2), which we highlight as potential candidates on the basis of several lines of evidence, and one of these genes (SLC39A14) was biallelically inactivated in a potentially treatable form of hypermanganesemia and neurodegeneration. Finally, likely causal variants in previously published candidate genes were identified (ASTN1, HELZ, THOC6, WDR45B, ADRA2B and CLIP1), thus supporting their involvement in ID pathogenesis. Our results expand the morbid genome of ID and support the adoption of genomics as a first-tier test for individuals with ID.
This study investigated whole-exome sequencing (WES) yield in a subset of intellectually disabled patients referred to our clinical diagnostic center and calculated the total costs of these patients' ...diagnostic trajectory in order to evaluate early WES implementation.
We compared 17 patients' trio-WES yield with the retrospective costs of diagnostic procedures by comprehensively examining patient records and collecting resource use information for each patient, beginning with patient admittance and concluding with WES initiation. We calculated cost savings using scenario analyses to evaluate the costs replaced by WES when used as a first diagnostic tool.
WES resulted in diagnostically useful outcomes in 29.4% of patients. The entire traditional diagnostic trajectory average cost was $16,409 per patient, substantially higher than the $3,972 trio-WES cost. WES resulted in average cost savings of $3,547 for genetic and metabolic investigations in diagnosed patients and $1,727 for genetic investigations in undiagnosed patients.
The increased causal variant detection yield by WES and the relatively high costs of the entire traditional diagnostic trajectory suggest that early implementation of WES is a relevant and cost-efficient option in patient diagnostics. This information is crucial for centers considering implementation of WES and serves as input for future value-based research into diagnostics.Genet Med 18 9, 949-956.
Lamin B1 plays an important role in the nuclear envelope stability, the regulation of gene expression, and neural development. Duplication of LMNB1, or missense mutations increasing LMNB1 expression, ...are associated with autosomal-dominant leukodystrophy. On the basis of its role in neurogenesis, it has been postulated that LMNB1 variants could cause microcephaly. Here, we confirm this hypothesis with the identification of de novo mutations in LMNB1 in seven individuals with pronounced primary microcephaly (ranging from −3.6 to −12 SD) associated with relative short stature and variable degree of intellectual disability and neurological features as the core symptoms. Simplified gyral pattern of the cortex and abnormal corpus callosum were noted on MRI of three individuals, and these individuals also presented with a more severe phenotype. Functional analysis of the three missense mutations showed impaired formation of the LMNB1 nuclear lamina. The two variants located within the head group of LMNB1 result in a decrease in the nuclear localization of the protein and an increase in misshapen nuclei. We further demonstrate that another mutation, located in the coil region, leads to increased frequency of condensed nuclei and lower steady-state levels of lamin B1 in proband lymphoblasts. Our findings collectively indicate that de novo mutations in LMNB1 result in a dominant and damaging effect on nuclear envelope formation that correlates with microcephaly in humans. This adds LMNB1 to the growing list of genes implicated in severe autosomal-dominant microcephaly and broadens the phenotypic spectrum of the laminopathies.
Background. The COVID-19 pandemic is expected to have a substantial impact on people with an intellectual disability. The goal of the current study was to explore the experiences and needs of people ...with a mild intellectual disability during the COVID-19 lockdown period in the Netherlands.
Method. A descriptive qualitative methodology was conducted, using semi-structured individual interviews with six people with a mild intellectual disability. Data were analysed thematically.
Results. Three overarching themes were found: (i) Missing social contact and having people close; (ii) Being housebound has changed my daily life; and (iii) Hard to understand the preventive measures.
Conclusions. Important insights into the experiences and needs of people with a mild intellectual disability during the COVID-19 lockdown period were gained. These insights are valuable with respect to a potential second COVID-19 wave or a future infection-outbreak.
Congenital hypothyroidism (CHT) is a common cause of preventable mental retardation, and the quantification of intellectual disability due to CHT is needed to assess the public health benefit of ...newborn screening.
Review of published studies conducted among children born prior to the introduction of newborn screening for CHT and reporting cognitive test scores.
Population-based studies.
Children with clinically diagnosed CHT.
Thyroid hormone substitution.
Intelligence quotient (IQ) (mean and distribution).
The prevalence of recognised CHT rose from one in 6500 prior to screening to approximately one in 3000 with screening. In four population-based studies in high-income countries, among children with clinically diagnosed CHT 8-28% were classified as having intellectual disability (defined as an IQ <70) and the mean IQ was 85 (a leftward shift of 1 SD). Among children with subclinical CHT, the risk of overt intellectual disability was lower (zero in one study), but decreased intellectual potential and increased behavioural abnormalities were documented.
Although the prevalence of overt disability among children with CHT in the absence of screening may be less than previously estimated, the preventable burden of intellectual disability due to CHT is substantial and justifies newborn screening. However, changes in existing newborn screening protocols to capture more cases are unlikely to prevent overt cases of disability and should therefore be justified instead by the documentation of other benefits of early detection.
Koolen-de Vries syndrome (KdVS) is a rare disorder caused by haploinsufficiency of KAT8 regulatory NSL complex subunit 1 (KANSL1), which is characterized by intellectual disability, heart failure, ...hypotonia, and congenital malformations. To date, no effective treatment has been found for KdVS, largely due to its unknown pathogenesis. Using siRNA screening, we identified KANSL1 as an essential gene for autophagy. Mechanistic study shows that KANSL1 modulates autophagosome-lysosome fusion for cargo degradation via transcriptional regulation of autophagosomal gene, STX17. Kansl1
mice exhibit impairment in the autophagic clearance of damaged mitochondria and accumulation of reactive oxygen species, thereby resulting in defective neuronal and cardiac functions. Moreover, we discovered that the FDA-approved drug 13-cis retinoic acid can reverse these mitophagic defects and neurobehavioral abnormalities in Kansl1
mice by promoting autophagosome-lysosome fusion. Hence, these findings demonstrate a critical role for KANSL1 in autophagy and indicate a potentially viable therapeutic strategy for KdVS.
Background: While research indicates elevated behavioural and emotional problems in children with autism spectrum disorders (ASD) and decreased well‐being in their parents, studies do not typically ...separate out the contribution of ASD from that of associated intellectual disabilities (ID). We investigated child behavioural and emotional problems, and maternal mental health, among cases with and without ASD and ID in a large population‐representative sample.
Methods: Cross‐sectional comparison of child behavioural and emotional problems and maternal mental health measures among 18,415 children (5 to 16 years old), of whom 47 had an ASD, 51 combined ASD with ID, 590 had only ID, and the remainder were the comparison group with no ASD or ID.
Results: The prevalence of likely clinical levels of behavioural and emotional problems was highest among children with ASD (with and without ID). After controlling for age, gender, adversity, and maternal mental health, the presence of ASD and ID significantly and independently increased the odds for hyperactivity symptoms, conduct, and emotional problems. Emotional disorder was more prevalent in mothers of children with ASD (with or without ID). The presence of ASD, but not ID, significantly increased the odds for maternal emotional disorder. As has been found in previous research, positive maternal mental health was not affected by the presence of ASD or ID.
Conclusions: ASD and ID are independent risk factors for behavioural and emotional problems. ASD (but not ID) is positively associated with maternal emotional disorder. Approaches to diagnosing hyperactivity and conduct problems in children with ASD may need to be reconsidered.
Wiedemann‐Steiner syndrome (WSS) is an autosomal dominant disorder caused by monoallelic variants in KMT2A and characterized by intellectual disability and hypertrichosis. We performed a ...retrospective, multicenter, observational study of 104 individuals with WSS from five continents to characterize the clinical and molecular spectrum of WSS in diverse populations, to identify physical features that may be more prevalent in White versus Black Indigenous People of Color individuals, to delineate genotype–phenotype correlations, to define developmental milestones, to describe the syndrome through adulthood, and to examine clinicians' differential diagnoses. Sixty‐nine of the 82 variants (84%) observed in the study were not previously reported in the literature. Common clinical features identified in the cohort included: developmental delay or intellectual disability (97%), constipation (63.8%), failure to thrive (67.7%), feeding difficulties (66.3%), hypertrichosis cubiti (57%), short stature (57.8%), and vertebral anomalies (46.9%). The median ages at walking and first words were 20 months and 18 months, respectively. Hypotonia was associated with loss of function (LoF) variants, and seizures were associated with non‐LoF variants. This study identifies genotype–phenotype correlations as well as race‐facial feature associations in an ethnically diverse cohort, and accurately defines developmental trajectories, medical comorbidities, and long‐term outcomes in individuals with WSS.
The number of genes known to cause human monogenic diseases is increasing rapidly. For the extremely large, genetically and phenotypically heterogeneous group of intellectual disability (ID) ...disorders, more than 600 causative genes have been identified to date. However, knowledge about the molecular mechanisms and networks disrupted by these genetic aberrations is lagging behind. The fruit fly Drosophila has emerged as a powerful model organism to close this knowledge gap. This review summarizes recent achievements that have been made in this model and envisions its future contribution to our understanding of ID genetics and neuropathology. The available resources and efficiency of Drosophila place it in a position to tackle the main challenges in the field: mapping functional modules of ID genes to provide conceptually novel insights into the genetic control of cognition, tailored functional studies to improve 'next-generation' diagnostics, and identification of reversible ID phenotypes and medication. Drosophila's behavioral repertoire and powerful genetics also open up perspectives for modeling genetically complex forms of ID and neuropsychiatric disorders, which overlap in their genetic etiologies. In conclusion, Drosophila provides many opportunities to advance future medical genomics of early onset cognitive disorders.
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