12q21.2q22 deletion: a new patient

Expanding the phenotype of 12q21 deletions: A role of BTG1 in speech development?

We report on a female individual with feeding difficulties, constipation, poor overall growth, periventricular lesions resembling gliosis in brain MRI, recurrent otitis media with palsy of facial nerve, distinct facial features, and pronounced delay in speech development. The latter was the most prominent feature. Molecular karyotyping revealed a heterozygous de novo deletion of 4.353 Mb at chromosome 12q21.33q22. This report expands the number of described individuals with heterozygous deletions at 12q21.33, their clinical spectrum and highlights the clinical variability, even in individuals with deletion of the same genes. Furthermore, our findings indicate a role of BTG1 (OMIM *109580) in speech development.

A New 12q21 Deletion Syndrome: A Case Report and Literature Review

Diagnosis in children with physical and intellective anomalies is very challenging because of the wide spectrum of causes. Array-based comparative genomic hybridization (CGH) has acquired an important role in pediatric diagnostic work up. Interstitial deletion of the long arm of chromosome 12 are rare. To date, deletions including the 12q21 region were reported in only 13 patients. The main features are development delay, eyes and central nervous system anomalies, and heart and kidney defects. We describe a 3-year-old boy with a de novo 15 Mb deletion at 12q21.1q21.32, never reported in the last cases. By screening the critical region and reviewing the literature, we identified SYT1, PPP1R12A, and CEP290 such as pathogenetic genes.

12q21 Interstitial Deletions: Seven New Syndromic Cases Detected by Array-CGH and Review of the Literature

Interstitial deletions of the long arm of chromosome 12 are rare, with a dozen patients carrying a deletion in 12q21 being reported. Recently a critical region (CR) has been delimited and could be responsible for the more commonly described clinical features, such as developmental delay/intellectual disability, congenital genitourinary and brain malformations. Other, less frequent, clinical signs do not seem to be correlated to the proposed CR. We present seven new patients harboring non-recurrent deletions ranging from 1 to 18.5 Mb differentially scattered across 12q21. Alongside more common clinical signs, some patients have rarer features such as heart defects, hearing loss, hypotonia and dysmorphisms. The correlation of haploinsufficiency of genes outside the CR to specific signs contributes to our knowledge of the effect of the deletion of this gene-poor region of chromosome 12q. This work underlines the still important role of copy number variations in the diagnostic setting of syndromic patients and the positive reflection on management and family genetic counseling.

12q21 deletion syndrome: Narrowing the critical region down to 1.6 Mb including SYT1 and PPP1R12A

Deletions in the 12q21 region are rare and non-recurrent CNVs. To date, only 11 patients with deletions in this region have been reported in the literature. These patients most often presented with syndromic intellectual deficiency, ventriculomegaly or hydrocephalus, ectodermal abnormalities, growth retardation and renal and cardiac malformations, suggesting a recognizable microdeletion syndrome. We report three new patients with overlapping deletions of the 12q21 region, including the smallest deletion reported to date and the first case characterized by array CGH during pregnancy. We describe specific clinical findings and shared facial features as developmental delay, ectodermal abnormalities, ventriculomegaly or hydrocephalus, axial hypotonia or spastic diplegia, growth retardation, heart defect, hydronephrosis, ureteral reflux or horseshoe kidney, large thorax or pectus excavatum, syndactyly of 2-3 toes, pterygium coli or excess nuchal skin, large anterior fontanel, low set ears, prominent forehead, short-upturned nose with nostril hypoplasia, microretrognathia and hypertelorism. These new patients and a comprehensive review of the literature allow us to define a minimum critical region spanning 1.6 Mb in 12q21. By screening the critical region using prediction tools, we identified two candidate genes: SYT1and PPP1R12A.

Clinical correlates in children with autism spectrum disorder and CNVs: Systematic investigation in a clinical setting

Autism spectrum disorder (ASD) is associated with various molecular mechanisms including copy number variants (CNVs). We investigated possible associations between CNVs and ASD clinical correlates. We evaluated pertinent physical characteristics and phenotypic measures such as cognitive level, severity of ASD symptoms and comorbid conditions in ASD patients consecutively recruited over the study period. Children with causative (C-CNVs), non-causative (NC-CNVs) and without CNVs (W-CNVs) were compared. Out of 109 patients, 31 imbalances (16 duplications and 15 deletions) were detected in 25 subjects. Seven (6.4%) had C-CNVs and 18 (16.5%) had NC-CNVs. Paired post hoc comparisons with Bonferroni adjustment showed that dysmorphisms and microcephaly were significantly more frequent in the C-CNVs group. Patients with C-CNVs had more severe autistic core symptoms, while comorbid internalizing behavioral symptoms were more represented among participants with NC-CNVs. No significant differences were observed for distribution of macrocephaly, intellectual disability, epilepsy, isolated electroencephalogram abnormalities and studied neuroimaging characteristics among groups. Recurrent and rare C-CNVs highlighting genes relevant to neurodevelopment had a statistically higher occurrence in children with more severe ASD symptoms and further developmental abnormalities. This study documents the importance of measuring the physical and neurobehavioural correlates of ASD phenotypes to unravel the underlying molecular mechanisms in patient subgroups.