p.Ser252Trp and p.Pro253Arg mutations in FGFR2 gene causing Apert syndrome: the first clinical and molecular report of Indonesian patients

ASXL3 gene mutations inhibit cell proliferation and promote cell apoptosis in mouse cardiomyocytes by upregulating lncRNA NONMMUT063967.2

Congenital heart disease (CHD) is a serious condition with unknown etiology. In a recent study, a compound heterozygous mutation (c.3526C > T [p.Arg1176Trp] and c.4643A > G [p.Asp1548Gly]) in the ASXL3 gene was identified, which is associated with CHD. This mutation was overexpressed in HL-1 mouse cardiomyocyte cells, leading to increased cell apoptosis and decreased cell proliferation. However, whether this effect is mediated by long noncoding RNAs (lncRNAs) is yet to be determined. We identified the differences among lncRNA and mRNA profiles in mouse heart tissues using sequencing to explore this issue. We detected HL-1 cell proliferation and apoptosis through CCK8 and flow cytometry. Fgfr2, lncRNA, and Ras/ERK signaling pathway expressions were evaluated using quantitative real time polymerase chain reaction (qRT-PCR) and western blot (WB) assays. We also conducted functional investigations by silencing lncRNA NONMMUT063967.2. The sequencing revealed significant changes in lncRNA and mRNA profiles, with the expression of lncRNA NONMMUT063967.2 being significantly promoted in the ASXL3 gene mutations group (MT) while the expression of Fgfr2 being downregulated. The in vitro experiments showed that ASXL3 gene mutations inhibited the proliferation of cardiomyocytes and accelerated cell apoptosis by promoting the expression of lncRNAs (NONMMUT063967.2, NONMMUT063918.2, and NONMMUT063891.2), suppressing the formation of FGFR2 transcripts, and inhibiting the Ras/ERK signaling pathway. The decrease in FGFR2 had the same effect on the Ras/ERK signaling pathway, proliferation, and apoptosis in mouse cardiomyocytes as ASXL3 mutations. Further mechanistic studies revealed that suppression of lncRNA NONMMUT063967.2 and overexpression of FGFR2 reversed the effects of the ASXL3 mutations on the Ras/ERK signaling pathway, proliferation, and apoptosis in mouse cardiomyocytes. Therefore, ASXL3 mutation decreases FGFR2 expression by upregulating lncRNA NONMMUT063967.2, inhibiting cell proliferation and promoting cell apoptosis in mouse cardiomyocytes.

A novel FGFR2 (S137W) mutation resulting in Apert syndrome: A case report

RATIONALE

Apert syndrome (AS) is an autosomal dominant inheritance pattern of the most severe craniosynostosis syndrome. AS is characterized by synostosis of cranial sutures and acrocephaly, including brachycephaly, midfacial hypoplasia, and syndactyly of the hands and feet. Patients with AS often present with craniosynostosis, severe syndactyly, and skin, skeletal, brain, and visceral abnormalities.

PATIENT CONCERNS

A pregnant Chinese woman presented with a fetus at 23 + 5 weeks of gestation with suspected AS in a prenatal ultrasound examination. Following ultrasound, the pregnancy underwent spontaneous abortion. Gene sequencing was performed on the back skin of the dead fetus.

DIAGNOSIS

The diagnosis of AS was confirmed on the basis of clinical manifestations of the fetus, and a de novo mutation in the fibroblast growth factor receptor 2 (FGFR2) gene was identified.

INTERVENTIONS

The couple finally chose to terminate the pregnancy based on the ultrasonic malformations and the risk of the parents having a neonate with AS in the future is small. However, any future pregnancy must be assessed by prenatal diagnosis.

OUTCOMES

The dead fetus presented with bilateral skull deformation. Additionally, there were bilateral changes to the temporal bone caused by inwards movement leading to concave morphology, a "clover" sign, and syndactyly from the index finger/second toe to the little finger/little toe. AS was diagnosed by genetic testing, which showed a p.S137W (c.410C>G, chr10:123279677) mutation in the FGFR2 gene.

LESSONS

Clinicians should be aware that there are a variety of ultrasound findings for AS. Therefore, genetic testing should be used when appropriate to confirm diagnosis of AS.

Molecular analysis of exon 7 of the fibroblast growth factor receptor 2 (FGFR2) gene in an Indonesian patient with Apert syndrome: a case report

BACKGROUND

Apert syndrome, Online Mendelian Inheritance in Man number 101200, is a rare genetic condition, with autosomal dominant inheritance, characterized by craniosynostosis, midfacial malformation, and severe symmetrical syndactyly. Apert syndrome is associated with other systemic malformations, including intellectual disability. At least seven mutations in fibroblast growth factor receptor 2 (FGFR2) gene have been found to cause Apert syndrome. Most cases of Apert syndrome are caused by one of the two most frequent mutations located in exon 7 (Ser252Trp or Pro253Arg).

CASE PRESENTATION

A 27-year-old Javanese man presented borderline intellectual functioning and striking dysmorphisms. A clinical diagnosis of Apert syndrome was previously made based on these clinical features. Furthermore, POSSUM software was used before molecular analysis and the result showed suspected Apert syndrome with a cut-off point of 14. Molecular genetic analysis of FGFR2, targeting exon 7, was performed by direct sequencing. In this patient, a missense mutation c.755C>G was detected, changing a serine into a tryptophan (p.Ser252Trp).

CONCLUSION

We report the case of an Indonesian man with Apert syndrome with a c.755C>G (p.Ser252Trp) mutation in the FGFR2 gene. Our patient showed similar dysmorphism to previously reported cases, although cleft palate as a typical feature for p.Ser252Trp mutation was not present. In spite of the accessibility of molecular genetic testing in a few parts of the world, the acknowledgement of clinically well-defined syndromes will remain exceptionally imperative in developing countries with a lack of diagnostic facilities.

Research advances in Apert syndrome

Apert syndrome is one of the several genetic syndromes associated with craniosynostosis, a condition that includes premature fusion of one or multiple cranial sutures. There has been significant clinical variation among different sutural synostoses and also within particular suture synostosis. Enormous progress has been made in identifying various mutations associated with Apert Syndrome. Although a causal gene has been defined, the precise role of this mutation in producing craniofacial dysmorphology and other related abnormalities is in the process of discovery. Most of the understanding regarding this rare disorder has been possible due to mouse models that have helped in deciphering the elements of this rare human disease. Thus, molecular and cellular understanding of the disease has taken a leap and further with the advent of technology definitive diagnosis of the syndrome is no more of an issue. In this review, we have discussed and consolidated the possible molecular studies that have contributed in understanding of this rare syndrome. This article may help clinicians and researchers to inform about the latest progress in Apert syndrome.

Apert syndrome with S252W FGFR2 mutation and characterization using Phenomizer: An Indian case report

Human genetic disease needs differential diagnosis to optimize clinical management, enable prenatal detection, and genetic counselling. The current methods of robust DNA sequencing also require next generation phenotyping to match with for better interpretation of genotypic and phenotypic heterogeneity commonly observed. We report use of human ontology based phenotypic characterization with Phenomizer that gives statistical score for possible diagnoses based on which, the gene mutation was studied. A case of craniosynostosis which refers to a group of syndromes characterized by a premature fusion of skull was studied. The phenotypic features viz, dental crowding and dental malocclusion, bulbous nose, downslanted palpebral fissures, radial deviation of thumb, syndactyly of fingers, macrocephaly, and oxycephaly were entered to query the web-based tool Phenomizer which indicated high probability of mutation in FGFR2 gene. The proband, a 13-year-old male born to non-consanguineous parents showed mutation on FGFR2 gene at c.755C>G indicative of Apert syndrome. Apert syndrome is one of the most severe craniosynostosis syndromes with two possible mutations in the exon IIIa of FGFR2 gene reported in majority of the cases. This case study shows the importance of Phenomizer and molecular genetic analysis in differential diagnosis of genetic diseases.

Atypical presentation of a newborn with Apert syndrome

INTRODUCTION

Apert syndrome is a rare syndrome characterized by a consistent phenotype including bilateral coronal suture synostosis with an enlarged anterior fontanel, midface hypoplasia, and complex symmetric syndactyly of hands and feet.

CASE REPORT

We present a boy with Apert syndrome caused by the pathogenic c.755C > G p.Ser252Trp mutation in the FGFR2 gene with atypical characteristics, including premature fusion of the metopic suture with a small anterior fontanel, hypotelorism, and a massive posterior fontanel. Directly after birth, he showed papilledema, epilepsy, and central apneas.

CONCLUSION

We present a newborn with Apert syndrome with atypical craniofacial presentation.

A novel heterozygous mutation of three consecutive nucleotides causing Apert syndrome in a Congolese family

Apert syndrome (OMIM 101200) is a rare genetic condition characterized by craniosynostosis and syndactyly of hands and feet with clinical variability. Two single nucleotides mutations in the linker region between the immunoglobulin-like domains II and IIIa of the ectodomainin the Fibroblast Growth Factor Receptor 2 gene (FGFR2, OMIM 176943) are responsible of the vast majority of cases: c.755C > G; p.Ser252Trp (65%) and c.758C > G; p.Pro253Arg (34%. Three exceptional cases carry multiple substitutions of adjacent nucleotides in the linker region. Here we present a Congolese male patient and his mother, both affected with Apert syndrome of variable severity, carrying a previously undescribed heterozygous mutation of three consecutive nucleotides (c.756_758delGCCinsCTT) in the IgII-IgIIIa linker region. This is the fourth live-born patient to carry a multiple nucleotide substitution in the linker region and is the second alternative amino acid substitutions of the Pro253. Remarkably, this novel mutation was detected in the first Central African patient ever to be tested molecularly for the Apert syndrome. To discriminate between a hitherto unreported mutation and an ethnic specific polymorphism, we tested 105 Congolese controls, and no variation was detected.