Noonan syndrome-like phenotype in a patient with heterozygous ERF truncating variant

Heterozygous variants disrupting the interaction of ERF with activated ERK1/2 cause microcephaly, developmental delay, and skeletal anomalies

Heterozygous deleterious null alleles and specific missense variants in the DNA-binding domain of the ETS2 repressor factor (ERF) cause craniosynostosis, while the recurrent p.(Tyr89Cys) missense variant is associated with Chitayat syndrome. Exome and whole transcriptome sequencing revealed the ERF de novo in-frame indel c.911_913del selectively removing the serine of the FSF motif, which interacts with the extracellular signal-regulated kinases (ERKs), in a 10-year-old girl with microcephaly, multiple congenital joint dislocations, generalized joint hypermobility, and Pierre-Robin sequence. Three additional cases with developmental delay variably associated with microcephaly, Pierre-Robin sequence and minor skeletal anomalies were detected carrying heterozygous de novo non-truncating alleles (two with c.911_913del and one with the missense c.907 T > A change) in the same FSF motif. Protein affinity maps, co-immunoprecipitation experiments and subcellular distribution showed that both the variants impair the interaction between ERF and activated ERK1/2 and increase ERF nuclear localization, affecting ERF repressor activity that may lead to developmental defects. Our work expands the phenotypic spectrum of ERF-related disorders to a pleiotropic condition with microcephaly, developmental delay and skeletal anomalies, that we termed MIDES syndrome, and adds to the understanding of the relevance of the ERF-ERK interaction in human development and disease.

Noonan syndrome-like phenotype associated with an ERF frameshift variant

Noonan syndrome is a so-called "RASopathy," that is characterized by short stature, distinctive facial features, congenital heart defects, and developmental delay. Of individuals with a clinical diagnosis of Noonan syndrome, 80%-90% have pathogenic variants in the known genes implicated in the disorder, but the molecular mechanism is unknown in the remaining cases. Heterozygous pathogenic variants of ETS2 repressor factor (ERF), which functions as a repressor in the RAS/MAPK signaling pathway, cause syndromic craniosynostosis. Here, we report an ERF frameshift variant cosegregating with a Noonan syndrome-like phenotype in a family. The proband was a 3-year-old female who presented with dysmorphic facial features, including proptosis, hypertelorism, slightly down slanted palpebral fissures, low-set posteriorly rotated ears, depressed nasal bridge, short stature, and developmental delay. Exome sequencing of the proband identified a heterozygous ERF variant [NM_006494.4: c.185del p.(Glu62Glyfs*15)]. Her mother and sister showed a similar phenotype and had the same heterozygous ERF variant. A large proportion of the previously reported patients with syndromic craniosynostosis and pathogenic ERF variants also showed characteristic features that overlap with those of Noonan syndrome. The present finding supports an association between heterozygous ERF variants and a Noonan syndrome-like phenotype.

Loss-of-function variants in ERF are associated with a Noonan syndrome-like phenotype with or without craniosynostosis

Pathogenic, largely truncating variants in the ETS2 repressor factor (ERF) gene, encoding a transcriptional regulator negatively controlling RAS-MAPK signaling, have been associated with syndromic craniosynostosis involving various cranial sutures and Chitayat syndrome, an ultrarare condition with respiratory distress, skeletal anomalies, and facial dysmorphism. Recently, a single patient with craniosynostosis and a phenotype resembling Noonan syndrome (NS), the most common disorder among the RASopathies, was reported to carry a de novo loss-of-function variant in ERF. Here, we clinically profile 26 individuals from 15 unrelated families carrying different germline heterozygous variants in ERF and showing a phenotype reminiscent of NS. The majority of subjects presented with a variable degree of global developmental and/or language delay. Their shared facial features included absolute/relative macrocephaly, high forehead, hypertelorism, palpebral ptosis, wide nasal bridge, and low-set/posteriorly angulated ears. Stature was below the 3rd centile in two-third of the individuals, while no subject showed typical NS cardiac involvement. Notably, craniosynostosis was documented only in three unrelated individuals, while a dolichocephalic aspect of the skull in absence of any other evidence supporting a premature closing of sutures was observed in other 10 subjects. Unilateral Wilms tumor was diagnosed in one individual. Most cases were familial, indicating an overall low impact on fitness. Variants were nonsense and frameshift changes, supporting ERF haploinsufficiency. These findings provide evidence that heterozygous loss-of-function variants in ERF cause a "RASopathy" resembling NS with or without craniosynostosis, and allow a first dissection of the molecular circuits contributing to MAPK signaling pleiotropy.

Cognitive, Behavioural, Speech, Language and Developmental Outcomes Associated with Pathogenic Variants in the ERF Gene

ABSTRACT

Pathogenic variants of the ERF gene were previously associated with craniosynostosis, craniofacial dysmorphism and Chiari malformation. This study investigates cognitive, behavioural, speech, language, and developmental outcomes in the first 5 children identified at the Oxford Craniofacial Unit as having ERF-related craniosynostosis, together with three of their carrier parents.There were no consistent findings related to overall intelligence. However, a pattern of cognitive difficulties is described, which includes poor attention, impulsivity and difficulties with functional fine motor skills, such as handwriting. A high frequency of speech, language and communication difficulties was evident, which was most often related to early language difficulties, speech sound difficulties, hyponasal resonance and concern regarding social communication skills and emotional immaturity.It was common for these children to have needed input from ear, nose and throat services. Problems with tonsils and/or adenoids and/ or fluctuating conductive hearing loss were found which may be contributors to early speech, language and communication difficulties.The authors make recommendations regarding the need for formal assessment of a range of developmental aspects upon diagnosis of a pathogenic variant in the ERF gene. The aim of this report is to give clinical guidance to anyone who may have care of patients with the ERF-related mutation.