ABSTRACT
Dubowitz syndrome (DubS) is considered a recognizable syndrome characterized by a distinctive facial appearance and deficits in growth and development. There have been over 200 individuals reported with Dubowitz or a "Dubowitz-like" condition, although no single gene has been implicated as responsible for its cause. We have performed exome (ES) or genome sequencing (GS) for 31 individuals clinically diagnosed with DubS. After genome-wide sequencing, rare variant filtering and computational and Mendelian genomic analyses, a presumptive molecular diagnosis was made in 13/27 (48%) families. The molecular diagnoses included biallelic variants in SKIV2L, SLC35C1, BRCA1, NSUN2; de novo variants in ARID1B, ARID1A, CREBBP, POGZ, TAF1, HDAC8, and copy-number variation at1p36.11(ARID1A), 8q22.2(VPS13B), Xp22, and Xq13(HDAC8). Variants of unknown significance in known disease genes, and also in genes of uncertain significance, were observed in 7/27 (26%) additional families. Only one gene, HDAC8, could explain the phenotype in more than one family (N = 2). All but two of the genomic diagnoses were for genes discovered, or for conditions recognized, since the introduction of next-generation sequencing. Overall, the DubS-like clinical phenotype is associated with extensive locus heterogeneity and the molecular diagnoses made are for emerging clinical conditions sharing characteristic features that overlap the DubS phenotype.
Subject(s)
Eczema/diagnosis , Eczema/genetics , Genetic Predisposition to Disease , Growth Disorders/diagnosis , Growth Disorders/genetics , Histone Deacetylases/genetics , Intellectual Disability/diagnosis , Intellectual Disability/genetics , Microcephaly/diagnosis , Microcephaly/genetics , Repressor Proteins/genetics , Adolescent , Child , Child, Preschool , DNA Copy Number Variations/genetics , Eczema/pathology , Exome/genetics , Facies , Female , Genome, Human/genetics , Genomics/methods , Growth Disorders/pathology , Humans , Infant , Intellectual Disability/pathology , Male , Microcephaly/pathology , Phenotype , Exome SequencingABSTRACT
The cover image, by Rani A. Bashir et al., is based on the Original Article Lin-Gettig syndrome: Craniosynostosis expands the spectrum of the KAT6B related disorders, DOI: 10.1002/ajmg.a.38355.
Subject(s)
Craniosynostoses/pathology , Histone Acetyltransferases/genetics , Mutation , Phenotype , Craniosynostoses/genetics , Humans , SyndromeABSTRACT
We report two patients with sagittal craniosynostosis, hypoplastic male genitalia, agenesis of the corpus callosum, thyroid abnormalities, and dysmorphic features which include short palpebral fissures and retrognathia. The clinical presentation of both patients was initially thought to be suggestive of Lin-Gettig syndrome (LGS), a multiple malformation syndrome associated with craniosynostosis that was initially reported in two brothers in 1990, with a third patient reported in 2003. Our first patient was subsequently found through exome sequencing to have a de novo mutation in KAT6B, c.4572dupT, p.(Thr1525Tyrfs*16). The second patient was ascertained as possible LGS, but KAT6B mutation testing was pursued clinically after the identification of the KAT6B mutation in Patient 1, and identified a de novo mutation, c.4205_4206delCT, p.(Ser1402Cysfs*5). The phenotypic spectrum of KAT6B mutations has been expanding since identification of KAT6B mutations in genitopatellar syndrome (GPS) and Say Barber Biesecker Young Simpson (SBBYS) syndrome patients. We show that craniosynostosis, which has not been previously reported in association with KAT6B mutations, may be part of the genitopatellar/Say Barber Biesecker Young Simpson spectrum. These two patients also further demonstrate the overlapping phenotypes of genitopatellar and SBBYS syndromes recently observed by others. Furthermore, we propose that it is possible that one or more of the previous cases of LGS may have also been due to mutation in KAT6B, and that LGS may actually be a variant within the KAT6B spectrum and not a distinct clinical entity.