Brief report: peculiar evolution of autistic behaviors in two unrelated children with brachidactyly-mental retardation syndrome

Grouping-Induced Numerosity Biases Vary with Autistic-Like Personality Traits

Individuals with autism spectrum disorder are thought to have a more local than global perceptual style. We used a novel paradigm to investigate how grouping-induced response biases in numerosity judgments depend on autistic-like personality traits in neurotypical adults. Participants judged the numerosity of clouds of dot-pairs connected by thin lines, known to cause underestimation of numerosity. The underestimation bias correlated strongly with autism-spectrum quotient (r = 0.72, Bayes factor > 100), being weaker for participants with high autistic traits. As connecting dots probably activates global grouping mechanisms, causing dot-pairs to be processed as an integrated whole rather than as individual dots, the results suggest that these grouping mechanisms may be weaker in individuals self-reporting high levels of autistic-like traits.

Genotype and phenotype correlation in 103 individuals with 2q37 deletion syndrome reveals incomplete penetrance and supports HDAC4 as the primary genetic contributor

The 2q37 deletion syndrome, also described in the literature as brachydactyly-mental retardation syndrome (MIM 600430), is caused by deletion or haploinsufficiency of the HDAC4 gene, which encodes the histone deacetylase 4 protein. Although the most commonly described hallmark features of the 2q37 deletion syndrome include brachydactyly type E, developmental delay, obesity, autistic features, and craniofacial or skeletal dysmorphism, a literature review of 101 published cases plus two newly reported individuals indicates that there is a high degree of variability in the presence of some of the features that are considered the most characteristic of the syndrome: overweight and obesity (34%), cognitive-behavioral issues (79%), dysmorphic craniofacial features (86%), and type E brachydactyly (48%). These features overlap with other neurodevelopmental conditions, including Smith-Magenis syndrome (SMS), and may be incompletely penetrant or demonstrate variable expressivity, depending on the specific chromosomal anomaly. With the advent of fluorescence in situ hybridization (FISH), array-based comparative genomic hybridization, and next-generation DNA sequencing, more detailed molecular diagnoses are possible than in years past, enabling refined characterization of the genotype-phenotype correlation for subjects with 2q37 deletions. In addition, investigations into molecular and gene expression networks are expanding in neurodevelopmental conditions, and we surveyed HDAC4 downstream gene expression by quantitative real-time polymerase chain reaction, further implicating HDAC4 in its role in the regulation of RAI1. Correlation of clinical data defining the impact on downstream gene expression and the potential clinical associations across neurodevelopment will improve our understanding of these complex conditions and potentially lead to common therapeutic approaches.

Brachydactyly Mental Retardation Syndrome Diagnosed in Adulthood

Brachydactyly mental retardation syndrome (BDMR) is due to a rare, small chromosomal deletion of 2q37, and manifests with variable signs and symptoms in people who live with it. BDMR could be misdiagnosed as Albright hereditary osteodystrophy (AHO), because it presents with lack of hormone resistance to parathyroid hormone (PTH) and similar skeletal and craniofacial abnormalities; however, BDMR is far rarer and can present with a different phenotype. In some cases, BDMR patients exhibit malformations of the internal organs, which could cause life-threatening health issues. Associations have also been made between this chromosomal deletion and autism as well. We here report a case of BDMR with an AHO-like phenotype: mild mental retardation, along with normal calcium, phosphate, and PTH levels. Since our patient had a normal biochemical test, we considered pseudopseudohypoparathyroidism (PPHP) as the diagnosis and genetic testing was performed. Karyotype analysis showed deletion of the long q-arm of chromosome 2 in all analyzed cells-46 XX, del (2)(q37.1), which was consistent with BDMR. This deletion is a loss of around 100 genes that can present itself in various ways neurologically and physiologically, depending on the genes lost. However, because patients experience a range of symptoms such as autism, seizures, heart defects, brachydactyly, there could be unforeseen complications with BDMR. Therefore, we postulate that it is necessary to consider a diagnosis of BDMR in adults with AHO-like phenotype and normal calcium metabolism.

Deletion 2q37 syndrome: Cognitive-behavioral trajectories and autistic features related to breakpoint and deletion size

Subtelomeric deletions have been reported in ∼2.5% of individuals with developmental disabilities. Subtelomeric deletion 2q37 has been detected in many individuals diagnosed with intellectual disabilities (ID) and autism spectrum disorders (ASD). Previously, genotype-phenotype correspondences were examined for their relationship to breakpoints 37.1, 37.2, or 37.3. Our purpose was to ascertain whether there were phenotypic differences at these breakpoints, elucidate the cognitive-behavioral phenotype in del2q37, and examine the genotype-phenotype association in the deletion with respect to cognitive-behavioral profiles and ASD. We administered a comprehensive cognitive-behavioral battery to nine children diagnosed with del 2q37, ages 3.9-17.75 years. ID for five tested with the Stanford-Binet (4th Edition) (SBFE) ranged from severe to mild [IQ Range: 36-59]. Adaptive behavior scores from the Vineland Adaptive Behavior Scale (VABS) were much below adequate levels (DQ Range: floor value ["19"] to 55). Autism scores from the Child Autism Rating Scale (CARS) ranged from 22 [non-autistic] to 56 [extremely autistic]; 5/8 [63%] children received scores on the autism spectrum. Participants with the largest deletions, 10.1 and 9.5 Mb, attained the highest IQ and DQ scores while those with the smallest deletions, 7.9 and 6.6 Mb, made the lowest IQ and DQ scores. No association between deletion breakpoint and phenotype were found. Assessment of the various deleted regions suggested histone deacetylase 4 gene (HDAC4) was a likely candidate gene for ASD in our sample. However, two earlier reports found no association between HDAC4 haploinsufficiency and ASD. © 2016 Wiley Periodicals, Inc.

Neuropsychological profiles of patients with 2q37.3 deletion associated with developmental dyspraxia

Patients with 2q37 deletions manifest brachydactyly mental retardation syndrome (BDMR). Recent advances in human molecular research have revealed that alterations in the histone deacetylase 4 gene (HDAC4) are responsible for the clinical manifestations of BDMR. Here, we report two male patients with 2q37.3 deletions. One of the patients showed a typical BDMR phenotype, and HDAC4 was included in the deletion region. HDAC4 was preserved in the other patient, and he showed a normal intelligence level with the delayed learning of complex motor skills. Detailed neuropsychological examinations revealed similar neuropsychological profiles in these two patients (visuo-spatial dyspraxia) that suggested developmental dyspraxia. These observations suggested that some other candidate genes for neuronal development exist in the telomeric region of HDAC4.

The 2q37-deletion syndrome: an update of the clinical spectrum including overweight, brachydactyly and behavioural features in 14 new patients

The 2q37 locus is one of the most commonly deleted subtelomeric regions. Such a deletion has been identified in >100 patients by telomeric fluorescence in situ hybridization (FISH) analysis and, less frequently, by array-based comparative genomic hybridization (array-CGH). A recognizable '2q37-deletion syndrome' or Albright's hereditary osteodystrophy-like syndrome has been previously described. To better map the deletion and further refine this deletional syndrome, we formed a collaboration with the Association of French Language Cytogeneticists to collect 14 new intellectually deficient patients with a distal or interstitial 2q37 deletion characterized by FISH and array-CGH. Patients exhibited facial dysmorphism (13/14) and brachydactyly (10/14), associated with behavioural problems, autism or autism spectrum disorders of varying severity and overweight or obesity. The deletions in these 14 new patients measured from 2.6 to 8.8 Mb. Although the major role of HDAC4 has been demonstrated, the phenotypic involvement of several other genes in the deleted regions is unknown. We further refined the genotype-phenotype correlation for the 2q37 deletion. To do this, we examined the smallest overlapping deleted region for candidate genes for skeletal malformations (facial dysmorphism and brachydactyly), overweight, behavioural problems and seizures, using clinical data, a review of the literature, and the Manteia database. Among the candidate genes identified, we focus on the roles of PRLH, PER2, TWIST2, CAPN10, KIF1A, FARP2, D2HGDH and PDCD1.