Growth, development, and phenotypic spectrum of individuals with deletions of 2q33.1 involving SATB2

Behaviours that Challenge in SATB2-associated Syndrome: Correlates of Self-injury, Aggression and Property Destruction

SATB2-associated syndrome (SAS) is a genetic syndrome characterised by intellectual disability, severe speech delay, and palatal and dental problems. Behaviours that challenge (BtC) are reported frequently; however, there is limited research on specific forms of BtC and the correlates of these behaviours. The current study explores correlates of well-defined BtC, self-injury, aggression, and property destruction, in SAS. Eighty-one parents/caregivers of individuals with SAS (53.1% male, Mage 10.12 years) completed questionnaire measures of health, behavioural, emotional, and autism characteristics. Individuals with SAS were grouped based on caregiver responses to the presence or absence of self-injury, aggression, and property destruction on the Challenging Behaviour Questionnaire. Rates of self-injury, aggression and property destruction were 42%, 77% and 49%, respectively. Between-group comparisons were conducted to compare characteristics between behaviour groups. Significantly differing characteristics were entered into separate hierarchical logistic regressions for each form of BtC. Behavioural comparisons indicated variation in the characteristics associated with each behaviour. All hierarchical logistic regression models were significant (p < .001): self-injury (χ2(5) = 38.46, R2 = 0.571), aggression (χ2(4) = 25.12, R2 = 0.414), property destruction (χ2(4) = 23.70, R2 = 0.346), explaining between 34.6% and 57.1% of the variance in behaviour presence. This is the first study to identify correlates of self-injury, aggression, and property destruction in SAS. Variability in the characteristics associated with each behaviour highlights the importance of specificity when examining BtC. Understanding correlates of specific forms of BtC has important implications for informing SAS-associated pathways to behavioural outcomes and the implementation of tailored behavioural interventions.

Exonized Alu repeats in the 3'UTR of a CYP20A1_Alu-LT transcript act as a miRNA sponge

OBJECTIVE

Alu repeats have gained huge importance in the creation and modification of regulatory networks. We previously reported a unique isoform of human CYP20A1 i.e. CYP20A1_Alu-LT with 23 Alu repeats exonized in its 9 kb long 3'UTR with 4742 potential binding sites for 994 miRNAs. The role of this transcript was hypothesized as a potential miRNA sponge in primary neurons as its expression correlated with that of 380 genes having shared miRNA sites and enriched in neuro-coagulopathy. This study provides experimental evidence for the miRNA sponge activity of CYP20A1_Alu-LT in neuronal cell lines.

RESULTS

We studied the Alu-rich fragment of the CYP20A1_Alu-LT extended 3'UTR with > 10 binding sites for miR-619-5p and miR-3677-3p. Enrichment of the Alu-rich fragment with Ago2 confirmed miRNA association of this transcript. Cloning the fragment downstream of a reporter gene led to a 90% decrease in luciferase activity. Overexpression and knockdown studies revealed a positive correlation between the expression of CYP20A1_Alu-LT and miR-619-5p / miR-3677-3p target genes. GAP43, one of the key modulators of nerve regeneration, was significantly altered by the expression of CYP20A1_Alu-LT. This study, for the first time, provides evidence for a unique regulatory function of exonized Alu repeats as miRNA sponges.

Growth in individuals with SATB2-associated syndrome

SATB2-associated syndrome (SAS) is an autosomal dominant multisystemic disorder caused by alterations in the SATB2 gene. In addition to a predominant neurodevelopmental phenotype, individuals with SAS often present with feeding difficulties and growth retardation that persist past infancy. In this study, we present growth and measurement data from 211 individuals (53.6% male, 46.4% female) with SAS due to different molecular mechanisms. To delineate growth in this population, we constructed SAS-specific growth charts by sex from birth to 10 years of age. Smoothed SAS percentiles were superimposed with normative percentiles from WHO (birth to <24 months) and CDC (24 months to 10 years) growth charts. Individuals with SAS tend to display slower postnatal growth with 22.2% (32/144), 19.0% (26/137), and 21.6% having at least one weight, height, or weight-for-length /body mass index (BMI) measurement below -2 standard deviations, respectively. The SAS 50th centile BMI was consistently below the normative data 50th centile and negative mean Z-scores were seen across almost all age groups analyzed for both genders. Individuals with chromosomal abnormalities displayed significantly lower weight for age Z-score, height for age Z-scores, occipitofrontal head circumference for age Z-scores, and BMI for age Z-scores compared to either missense or null variants.

The behavioural phenotype of SATB2-associated syndrome: a within-group and cross-syndrome analysis

Background

SATB2-associated syndrome (SAS) is a multisystem neurodevelopmental disorder characterised by intellectual disability, speech delay, and craniofacial anomalies. Although the clinical presentation of SAS is well-delineated, behaviours associated with SAS are less well-defined. Given the varied social profile reported in SAS of a ‘jovial’ predisposition and autistic behaviours, there may be phenotypic overlap with both Angelman syndrome (AS) and non-syndromal autism. This study aimed to describe behaviours in SAS in relation to chronological age and level of ability and contrast aspects of the behavioural phenotype with AS and non-syndromal autism.

Methods

Informant report questionnaire measures of behaviour, emotion, and autism characteristics were completed for 81 individuals with SAS (aged 1–36 years; 43 male). Within-group associations were analysed, and categorical data were compared between pre-school (1–5 years), school-age (6–15 years), and adolescent and adult SAS sub-groups (16 years and over). Cross-syndrome subscale and item-level analyses were conducted for 63 individuals with SAS (aged 1–27 years; 31 male), who were matched according to age and level of ability to 63 individuals with AS (aged 2–25 years; 32 male) and 63 individuals with non-syndromal autism (aged 3–26 years; 53 male).

Results

In SAS, higher rates of overactivity were moderately associated with lower self-help ability, and higher general anxiety scores were reported for males compared with females. Cross-syndrome subscale analyses uncovered several significant differences (p < .01), with comparatively low rates of stereotyped behaviour, overactivity, insistence on sameness and positive affect, and comparatively greater interest and pleasure and compulsive behaviour in individuals with SAS. Item-level analyses revealed a distinct profile of repetitive and autistic behaviours.

Limitations

Developmental analysis was based on a cross-sectional rather than a longitudinal research design, the contribution of pain and sleep to behaviour was not explored, and molecular genetic testing to determine genotype–phenotype behavioural relationships was not possible.

Conclusions

This study highlights the importance of behavioural comparisons to well-delineated groups and the utility of fine-grained item-level analyses to elucidate aspects of behaviour that might be syndrome related or shared across neurodevelopmental disorders. Future research is needed to further describe the distinctive repetitive and autistic behavioural phenotype in SAS.

Supplementary Information

The online version contains supplementary material available at 10.1186/s11689-022-09426-0.

Update on the molecular landscape of thoracic aortic aneurysmal disease

PURPOSE OF THE REVIEW

Thoracic aortic aneurysms and dissections (TAADs) are a major health problem in the Western population. This review summarises recent discoveries in the genetic landscape of TAAD disease, discusses current challenges in clinical practice, and describes the molecular road ahead in TAAD research. Disorders, in which aneurysmal disease is not observed in the thoracic aorta, are not discussed.

RECENT FINDINGS

Current gene discovery studies have pinpointed about 40 genes associated with TAAD risk, accounting for about 30% of the patients. Importantly, novel genes, and their subsequent functional characterisation, have expanded the knowledge on disease-related pathways providing crucial information on key elements in this disease, and it pinpoints new therapeutic targets. Moreover, current molecular evidence also suggests the existence of less monogenic nature of TAAD disease, in which the presentation of a diseased patient is most likely influenced by a multitude of genetic and environmental factors.

SUMMARY CLINICAL PRACTICE/RELEVANCE

Ongoing molecular genetic research continues to expand our understanding on the pathomechanisms underlying TAAD disease in order to improve molecular diagnosis, optimise risk stratification, advance therapeutic strategies and facilitate counselling of TAAD patients and their families.

Orphan cytochrome P450 20a1 CRISPR/Cas9 mutants and neurobehavioral phenotypes in zebrafish

Orphan cytochrome P450 (CYP) enzymes are those for which biological substrates and function(s) are unknown. Cytochrome P450 20A1 (CYP20A1) is the last human orphan P450 enzyme, and orthologs occur as single genes in every vertebrate genome sequenced to date. The occurrence of high levels of CYP20A1 transcripts in human substantia nigra and hippocampus and abundant maternal transcripts in zebrafish eggs strongly suggest roles both in the brain and during early embryonic development. Patients with chromosome 2 microdeletions including CYP20A1 show hyperactivity and bouts of anxiety, among other conditions. Here, we created zebrafish cyp20a1 mutants using CRISPR/Cas9, providing vertebrate models with which to study the role of CYP20A1 in behavior and other neurodevelopmental functions. The homozygous cyp20a1 null mutants exhibited significant behavioral differences from wild-type zebrafish, both in larval and adult animals. Larval cyp20a1-/- mutants exhibited a strong increase in light-simulated movement (i.e., light-dark assay), which was interpreted as hyperactivity. Further, the larvae exhibited mild hypoactivity during the adaptation period of the optomotor assays. Adult cyp20a1 null fish showed a pronounced delay in adapting to new environments, which is consistent with an anxiety paradigm. Taken together with our earlier morpholino cyp20a1 knockdown results, the results described herein suggest that the orphan CYP20A1 has a neurophysiological role.

Individuals with SATB2-associated syndrome with and without autism have a recognizable metabolic profile and distinctive cellular energy metabolism alterations

SATB2-associated syndrome (SAS) is a multisystemic disorder characterized by developmental delay often with concurrent autistic tendencies. This study aimed to characterize cellular metabolic pathways and energy metabolism from cells derived from individuals with SAS. The cellular production of NADH (nicotinamide adenine dinucleotide, reduced form) as determined by the Phenotype Mammalian MicroArrays was measured in lymphoblastoid cell lines derived from 11 subjects with a molecularly confirmed diagnosis of SAS and compared to a control population of 50 age-matched typically developing individuals. All patients were evaluated clinically by a multidisciplinary team. Eleven individuals (five in a screening cohort and six in the validation cohort, mean age 6.1 years) were recruited to the study. All individuals had developmental delay and the diagnosis of autism was previously established in five of them. Key metabolic findings included reduced NADH production in the presence of phosphorylated carbohydrates (with corresponding increased production in the presence of alternative carbon-based energy sources), increased response to certain hormones (β-estradiol in particular), and significantly reduced levels of NADH in wells containing tryptophan. The individual analysis revealed no particular differences among the SAS subjects based on molecular findings or phenotypic features. In conclusion, individuals with SAS have a common and recognizable metabolic profile. A lower capacity to utilize glucose as an energy substrate could be contributing to the neurodevelopment phenotype of SAS. The identified abnormalities offer previously unexplored insight into the potential pathophysiology of common SAS phenotypic features.

SATB2-associated syndrome in adolescents and adults

The goal of this study was to investigate the medical, communication, activities of daily living (ADLs), and mental health concerns affecting adolescents and adults with SATB2-associated syndrome (SAS). A comprehensive questionnaire was administered to the caregivers of 49 individuals 12 years or older with SAS (mean age was 19.4 years, range 12-37 years). For all individuals, medical records, including laboratory results, were reviewed. Most individuals required some degree of assistance for ADLs and none of the adults were able to live independently. Health status was qualified as excellent or very good in 61% of individuals. The most common medical problems were dental anomalies, with a significantly higher frequency of hypotonia and gastroesophageal reflux in younger individuals. Medical and surgical interventions were often required. Sixty-nine percent (n = 33) of individuals spoke 10 or fewer words. Autism (41%), anxiety (37%), and attention deficit disorder (37%) were common with one third of individuals receiving medical treatments for these diagnoses. While medical and developmental problems in individuals with SAS were similar to those previously reported, many of these are persistent into adolescence and adulthood. This study provides better guidance for the challenges facing adults with SAS and their families.