Biallelic and monoallelic ESR2 variants associated with 46,XY disorders of sex development

Purpose Disorders or differences of sex development (DSDs) are rare congenital conditions characterized by atypical sex development. Despite advances in genomic technologies, the molecular cause remains unknown in 50% of cases. Methods Homozygosity mapping and whole-exome sequencing revealed an ESR2 variant in an individual with syndromic 46,XY DSD. Additional cases with 46,XY DSD underwent whole-exome sequencing and targeted next-generation sequencing of ESR2. Functional characterization of the identified variants included luciferase assays and protein structure analysis. Gonadal ESR2 expression was assessed in human embryonic data sets and immunostaining of estrogen receptor-β (ER-β) was performed in an 8-week-old human male embryo. Results We identified a homozygous ESR2 variant, c.541_543del p.(Asn181del), located in the highly conserved DNA-binding domain of ER-β, in an individual with syndromic 46,XY DSD. Two additional heterozygous missense variants, c.251G>T p.(Gly84Val) and c.1277T>G p.(Leu426Arg), located in the N-terminus and the ligand-binding domain of ER-β, were found in unrelated, nonsyndromic 46,XY DSD cases. Significantly increased transcriptional activation and an impact on protein conformation were shown for the p.(Asn181del) and p.(Leu426Arg) variants. Testicular ESR2 expression was previously documented and ER-β immunostaining was positive in the developing intestine and eyes. Conclusion Our study supports a role for ESR2 as a novel candidate gene for 46,XY DSD

Biallelic and monoallelic ESR2 variants associated with 46,XY disorders of sex development

Purpose: Disorders or differences of sex development (DSDs) are rare congenital conditions characterized by atypical sex development. Despite advances in genomic technologies, the molecular cause remains unknown in 50% of cases. Methods: Homozygosity mapping and whole-exome sequencing revealed an ESR2 variant in an individual with syndromic 46, XY DSD. Additional cases with 46, XY DSD underwent whole-exome sequencing and targeted next-generation sequencing of ESR2. Functional characterization of the identified variants included luciferase assays and protein structure analysis. Gonadal ESR2 expression was assessed in human embryonic data sets and immunostaining of estrogen receptor-beta (ER-beta) was performed in an 8-week-old human male embryo. Results: We identified a homozygous ESR2 variant, c.541_543del p. (Asn181del), located in the highly conserved DNA-binding domain of ER-beta, in an individual with syndromic 46, XY DSD. Two additional heterozygous missense variants, c.251G>T p.(Gly84Val) and c.1277T>G p.(Leu426Arg), located in the N-terminus and the ligand-binding domain of ER-beta, were found in unrelated, nonsyndromic 46, XY DSD cases. Significantly increased transcriptional activation and an impact on protein conformation were shown for the p.(Asn181del) and p.(Leu426Arg) variants. Testicular ESR2 expression was previously documented and ER-beta immunostaining was positive in the developing intestine and eyes. Conclusion: Our study supports a role for ESR2 as a novel candidate gene for 46, XY DSD

Biallelic sequence and structural variants in RAX2 are a novel cause for autosomal recessive inherited retinal disease.

Purpose RAX2 encodes a homeobox-containing transcription factor, in which four monoallelic pathogenic variants have been described in autosomal dominant cone-dominated retinal disease. Methods Exome sequencing in a European cohort with inherited retinal disease (IRD) (n = 2086) was combined with protein structure modeling of RAX2 missense variants, bioinformatics analysis of deletion breakpoints, haplotyping of RAX2 variant c.335dup, and clinical assessment of biallelic RAX2-positive cases and carrier family members. Results Biallelic RAX2 sequence and structural variants were found in five unrelated European index cases, displaying nonsyndromic autosomal recessive retinitis pigmentosa (ARRP) with an age of onset ranging from childhood to the mid-40s (average mid-30s). Protein structure modeling points to loss of function of the novel recessive missense variants and to a dominant-negative effect of the reported dominant RAX2 alleles. Structural variants were fine-mapped to disentangle their underlying mechanisms. Haplotyping of c.335dup in two cases suggests a common ancestry. Conclusion This study supports a role for RAX2 as a novel disease gene for recessive IRD, broadening the mutation spectrum from sequence to structural variants and revealing a founder effect. The identification of biallelic RAX2 pathogenic variants in five unrelated families shows that RAX2 loss of function may be a nonnegligible cause of IRD in unsolved ARRP cases

Biallelic loss-of-function variants in RAX2, encoding a homeobox-containing Rax transcription factor, cause autosomal recessive inherited retinal disease

RAX2 encodes a member of the homeobox-containing Rax family of transcription factors, which play a pivotal role in late retinogenesis in vertebrate species by regulating the spatial expression of photoreceptor-specific genes. So far, only four monoallelic RAX2 variants have been tentatively implicated in autosomal dominant cone-dominated retinal disease. Here we report biallelic missense, frameshift and structural variants in RAX2 identified by whole exome sequencing, in five unrelated index cases of Belgian, British, Italian and Spanish origin, diagnosed with non-syndromic autosomal recessive retinitis pigmentosa (RP) with a variable age of onset. Protein structure analysis of the two novel missense variants revealed a loss of Rax2 protein folding and/or stability, in agreement with a loss-of-function effect. Modeling of the previously reported dominant RAX2 missense variant on the other hand demonstrated potential roles in homeodomain/DNA higher order complex formation with no effect on protein stability or DNA binding, thus compatible with a gain-of-function effect. Haplotype analysis in three Belgian RP cases sharing the same RAX2 frameshift variant c.335dup suggested a common ancestry. Fine-mapping and bio-informatics analysis of the two identified structural variants affecting RAX2 disentangled their underlying mechanisms. In summary, our findings support a role for RAX2 as a novel disease gene for autosomal recessive RP. This study uncovered the first structural variants affecting RAX2 and a founder allele in Belgian RP patients. The identification of biallelic pathogenic RAX2 variants in five unrelated families may suggest a role in other autosomal recessive RP cases with an unknown molecular diagnosis

Structural basis of the proinflammatory signaling complex mediated by TSLP

Thymic stromal lymphopoietin (TSLP), a cytokine produced by epithelial cells at barrier surfaces, is pivotal for the development of widespread chronic inflammatory disorders such as asthma and atopic dermatitis. The structure of the mouse TSLP-mediated signaling complex reveals how TSLP establishes extensive interfaces with its cognate receptor (TSLPR) and the shared interleukin 7 receptor alpha-chain (IL-7R alpha) to evoke membrane-proximal receptor-receptor contacts poised for intracellular signaling. Binding of TSLP to TSLPR is a mechanistic prerequisite for recruitment of IL-7R alpha to the high-affinity ternary complex, which we propose is coupled to a structural switch in TSLP at the crossroads of the cytokine-receptor interfaces. Functional interrogation of TSLP-receptor interfaces points to putative interaction hotspots that could be exploited for antagonist design. Finally, we derive the structural rationale for the functional duality of IL-7R alpha and establish a consensus for the geometry of ternary complexes mediated by interleukin 2 (IL-2)-family cytokines