De Novo Disruption of the Proteasome Regulatory Subunit PSMD12 Causes a Syndromic Neurodevelopmental Disorder.

Degradation of proteins by the ubiquitin-proteasome system (UPS) is an essential biological process in the development of eukaryotic organisms. Dysregulation of this mechanism leads to numerous human neurodegenerative or neurodevelopmental disorders. Through a multi-center collaboration, we identified six de novo genomic deletions and four de novo point mutations involving PSMD12, encoding the non-ATPase subunit PSMD12 (aka RPN5) of the 19S regulator of 26S proteasome complex, in unrelated individuals with intellectual disability, congenital malformations, ophthalmologic anomalies, feeding difficulties, deafness, and subtle dysmorphic facial features. We observed reduced PSMD12 levels and an accumulation of ubiquitinated proteins without any impairment of proteasome catalytic activity. Our PSMD12 loss-of-function zebrafish CRISPR/Cas9 model exhibited microcephaly, decreased convolution of the renal tubules, and abnormal craniofacial morphology. Our data support the biological importance of PSMD12 as a scaffolding subunit in proteasome function during development and neurogenesis in particular; they enable the definition of a neurodevelopmental disorder due to PSMD12 variants, expanding the phenotypic spectrum of UPS-dependent disorders.

Nail and phalangeal agenesis in a patient with 4pter and 9pter duplication.

We report on an 8-month-old girl with intra-uterine growth retardation, microcephaly, incomplete cleft lip, axial hypotonia, failure to thrive, and brachydactyly type B (phalangeal agenesis and absence of nails). She carried a supernumerary marker chromosome derived from chromosomes 4 and 9, leading to 4pter-q12 and 9pter-p21.2 duplication. The marker was derived from the 3:1 segregation of a maternal balanced translocation 46,XX, t(4;9)(q12;p21.2). The proposita is the first reported individual with distal phalangeal agenesis and anonychia, and trisomy 4p and partial trisomy 9p due to 3:1 segregation of a maternal reciprocal translocation.

Aphallia, lung agenesis and multiple defects of blastogenesis.

We report the association of aphallia, with imperforate anus, bilateral renal dysplasia and complete right lung agenesis in a fetus born of non-consanguineous parents. No maternal diabetes was present. The multiple mesodermal anomalies present in this male fetus, with a severe form of Uro-Rectal-Septum Malformation Sequence associated with unilateral lung agenesis, and rib segmentation anomaly is consistent with an extended defect of blastogenesis, with apparent common timing of the malformations around the 5th to 7th weeks of gestation.

Unilateral agenesis of the abdominal wall musculature: An early muscle deficiency.

Prune-belly sequence (PBS) usually results from early urethral obstruction. In rare cases, PBS seems to be due to a faulty primary development of the parietal mesenchyme leading to underdevelopment of the abdominal wall musculature, and disorganization of the smooth muscles in the urinary tract. We report on two patients with segmental, unilateral wall musculature deficiency associated with homolateral agenesis of ribs. One patient also had hemivertebrae and the other one ipsilateral diaphragmatic eventration and aplasia cutis. This combination of anomalies may represent a localized deficiency in the development of somitic mesoderm mesenchyme during early embryogenesis.

Primrose syndrome: a phenotypic comparison of patients with a ZBTB20 missense variant versus a 3q13.31 microdeletion including ZBTB20.

Primrose syndrome is characterized by variable intellectual deficiency, behavior disorders, facial features with macrocephaly, and a progressive phenotype with hearing loss and ectopic calcifications, distal muscle wasting, and contractures. In 2014, ZBTB20 variants were identified as responsible for this syndrome. Indeed, ZBTB20 plays an important role in cognition, memory, learning processes, and has a transcription repressive effect on numerous genes. A more severe phenotype was discussed in patients with missense single nucleotide variants than in those with large deletions. Here, we report on the clinical and molecular results of 14 patients: 6 carrying ZBTB20 missense SNVs, 1 carrying an early truncating indel, and 7 carrying 3q13.31 deletions, recruited through the AnDDI-Rares network. We compared their phenotypes and reviewed the data of the literature, in order to establish more powerful phenotype-genotype correlations. All 57 patients presented mild-to-severe ID and/or a psychomotor delay. Facial features were similar with macrocephaly, prominent forehead, downslanting palpebral fissures, ptosis, and large ears. Hearing loss was far more frequent in patients with missense SNVs (p = 0.002), ectopic calcification, progressive muscular wasting, and contractures were observed only in patients with missense SNVs (p nonsignificant). Corpus callosum dysgenesis (p = 0.00004), hypothyroidism (p = 0.047), and diabetes were also more frequent in this group. However, the median age was 9.4 years in patients with deletions and truncating variant compared with 15.1 years in those with missense SNVs. Longer follow-up will be necessary to determine whether the phenotype of patients with deletions is also progressive.

Early-onset obesity and paternal 2pter deletion encompassing the ACP1, TMEM18, and MYT1L genes.

Obesity is a common but highly, clinically, and genetically heterogeneous disease. Deletion of the terminal region of the short arm of chromosome 2 is rare and has been reported in about 13 patients in the literature often associated with a Prader-Willi-like phenotype. We report on five unrelated patients with 2p25 deletion of paternal origin presenting with early-onset obesity, hyperphagia, intellectual deficiency, and behavioural difficulties. Among these patients, three had de novo pure 2pter deletions, one presented with a paternal derivative der(2)t(2;15)(p25.3;q26) with deletion in the 2pter region and the last patient presented with an interstitial 2p25 deletion. The size of the deletions was characterized by SNP array or array-CGH and was confirmed by fluorescence in situ hybridization (FISH) studies. Four patients shared a 2p25.3 deletion with a minimal critical region estimated at 1.97 Mb and encompassing seven genes, namely SH3HYL1, ACP1, TMEMI8, SNTG2, TPO, PXDN, and MYT1L genes. The fifth patient had a smaller interstitial deletion encompassing the TPO, PXDN, and MYT1L genes. Paternal origin of the deletion was determined by genotyping using microsatellite markers. Analysis of the genes encompassed in the deleted region led us to speculate that the ACP1, TMEM18, and/or MYT1L genes might be involved in early-onset obesity. In addition, intellectual deficiency and behavioural troubles can be explained by the heterozygous loss of the SNTG2 and MYT1L genes. Finally, we discuss the parent-of-origin of the deletion.