Three patients with DeSanto-Shinawi syndrome: Further phenotypic delineation.

Somatic truncating variants of the WAC gene have been observed in patients with hematologic malignancies. Furthermore, de novo heterozygous constitutional pathogenic variants of WAC have recently been shown to cause a syndromic form of intellectual disability, DeSanto-Shinawi syndrome. It is unknown whether the constitutional pathogenic variants observed in the intellectual disability syndrome overlap with the somatic pathogenic variants observed in hematologic abnormalities. Herein, we report three patients with constitutional truncating variants of WAC in an attempt to address the above questions. All three of the patients had mild to moderate intellectual disability and dysmorphic features. We then reviewed the phenotypic features of 19 patients with DeSanto-Shinawi syndrome, including the three currently reported ones: eight and seven patients showed a bulbous nasal tip and short fingers, respectively. As for the pathogenetic mechanism, we demonstrated that the expression level of the mRNA derived from the wildtype allele was higher than that derived from the mutated allele, demonstrating nonsense-mediated mRNA decay. This observation makes a haploinsufficiency mechanism likely. Reviews of the constitutional and somatic pathogenic variants observed in patients with hematologic malignancies showed a significant overlap of the two. To date, no patients with DeSanto-Shinawi syndrome have been reported to have developed hematologic abnormalities, except for one of the three patients reported herein who developed leukopenia and thrombocytopenia at the age of 19 years. Larger data sets are required to determine hematologic prognosis of patients with constitutional WAC variants.

Microarray and FISH-based genotype-phenotype analysis of 22 Japanese patients with Wolf-Hirschhorn syndrome.

Wolf-Hirschhorn syndrome (WHS) is a contiguous gene deletion syndrome of the distal 4p chromosome, characterized by craniofacial features, growth impairment, intellectual disability, and seizures. Although genotype-phenotype correlation studies have previously been published, several important issues remain to be elucidated including seizure severity. We present detailed clinical and molecular-cytogenetic findings from a microarray and fluorescence in situ hybridization (FISH)-based genotype-phenotype analysis of 22 Japanese WHS patients, the first large non-Western series. 4p deletions were terminal in 20 patients and interstitial in two, with deletion sizes ranging from 2.06 to 29.42 Mb. The new Wolf-Hirschhorn syndrome critical region (WHSCR2) was deleted in all cases, and duplication of other chromosomal regions occurred in four. Complex mosaicism was identified in two cases: two different 4p terminal deletions; a simple 4p terminal deletion and an unbalanced translocation with the same 4p breakpoint. Seizures began in infancy in 33% (2/6) of cases with small (<6 Mb) deletions and in 86% (12/14) of cases with larger deletions (>6 Mb). Status epilepticus occurred in 17% (1/6) with small deletions and in 87% (13/15) with larger deletions. Renal hypoplasia or dysplasia and structural ocular anomalies were more prevalent in those with larger deletions. A new susceptible region for seizure occurrence is suggested between 0.76 and 1.3 Mb from 4 pter, encompassing CTBP1 and CPLX1, and distal to the previously-supposed candidate gene LETM1. The usefulness of bromide therapy for seizures and additional clinical features including hypercholesterolemia are also described.