Dysmorphism, variable overgrowth, normal bone age, and severe developmental delay: a "Sotos-like" syndrome?

Molecular Analysis and Reclassification of NSD1 Gene Variants in a Cohort of Patients with Clinical Suspicion of Sotos Syndrome

Sotos syndrome is a rare genetic disorder caused by haploinsufficiency of the NSD1 (nuclear receptor binding SET domain containing protein 1) gene. No clinical diagnostic consensus criteria are published yet, and molecular analysis reduces the clinical diagnostic uncertainty. We screened 1530 unrelated patients enrolled from 2003 to 2021 at Galliera Hospital and Gaslini Institute in Genoa. NSD1 variants were identified in 292 patients including nine partial gene deletions, 13 microdeletions of the entire NSD1 gene, and 115 novel intragenic variants never previously described. Thirty-two variants of uncertain significance (VUS) out of 115 identified were re-classified. Twenty-five missense NSD1 VUS (25/32, 78.1%) changed class to likely pathogenic or likely benign, showing a highly significant shift in class (p < 0.01). Apart from NSD1, we identified variants in additional genes (NFIX, PTEN, EZH2, TCF20, BRWD3, PPP2R5D) in nine patients analyzed by the NGS custom panel. We describe the evolution of diagnostic techniques in our laboratory to ascertain molecular diagnosis, the identification of 115 new variants, and the re-classification of 25 VUS in NSD1. We underline the utility of sharing variant classification and the need to improve communication between the laboratory staff and the referring physician.

Sotos Syndrome: A case report

Sotos Syndrome is a genetic condition characterized by accelerated bone development, abnormal craniofacial morphology and psychomotor developmental retardation. The behavioral problems usually associated with the syndrome include poor social skills, anxiety and/or irritability. Oral findings include prognathism and a high-arched palate with premature eruption of the teeth. Delayed psychomotor development increases the risk for caries. A personalized preventive treatment plan with close supervision of the patient's oral health care is required. This paper documents a child diagnosed with Sotos Syndrome and describes the primary clinical features, the disease-specific craniofacial, oral and dental findings, and dental care management of this patient.

Overgrowth with severe developmental delay following IVF/ICSI: A newly recognized syndrome?

We report on a child with postnatal overgrowth, noted from 3 months of age, associated with severe developmental delay and refractory seizures. The patient was conceived using in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI). The patient's features do not resemble any reported overgrowth syndromes reported so far. We propose that this is a previously unrecognized disorder. The potential role of ICSI/IVF in the pathogenesis of this condition is unknown. No imprinting defect at chromosome 11p15 was identified.

NSD1 mutations in Sotos syndrome

Sotos syndrome is a genetic disorder characterized by a typical facial appearance, macrocephaly, accelerated growth, developmental delay, and a variable range of associated abnormalities. The NSD1 gene was recently found to be responsible for Sotos syndrome, and more than 150 patients with NSD1 alterations have been identified. A significant ethnic difference is found in the prevalence of different types of mutation, with a high percentage of microdeletions identified in Japanese Sotos syndrome patients and with intragenic mutations in most non-Japanese patients. NSD1 aberrations are rather specific for Sotos syndrome, but have also been detected in patients lacking one or more major criteria of the disorder, namely overgrowth, macrocephaly, and advanced bone age. Thus, new diagnostic criteria should be considered. Studies have reported different frequencies of mutations versus non-mutations in Sotos syndrome, thus indicating allelic or locus hetereogeneity. Although some authors have suggested genotype/phenotype correlations, further studies are needed.