A novel mutation of the fibrillin-1 gene in a newborn with severe Marfan syndrome

Neonatal Marfan syndrome: a case report of a novel fibrillin 1 mutation, with genotype-phenotype correlation and brief review of the literature

BACKGROUND

Neonatal Marfan syndrome (nMFS) is a rare condition characterized by severe phenotype and poor prognosis. nMFS is caused by mutations in a specific region of the fibrillin 1 gene (FBN1). Prompt recognition of typical signs of neonatal presentation, such as characteristic facial anomalies with senile appearance, arthrogryposis, and campto-arachnodactyly, is fundamental for performing an early cardiological examination. This usually reveals rapidly progressive cardiovascular disease due to severe atrioventricular valve dysfunction.

CASE PRESENTATION

Herein, we report the case of an early-onset cardiac failure in a neonate with Marfan syndrome, with a brief review of the literature of cases with cardiac involvement in neonatal age. Clinical exome sequencing identified the novel heterozygous de novo missense variant c.3152T > G in FBN1 gene (NM_000138.4), causing the aminoacidic change p.Phe1051Cys. Phenotype-genotype correlation led to a multidisciplinary diagnostic and management workflow.

CONCLUSION

The prompt recognition of a typical phenotype such as that of Marfan syndrome should lead to a detailed evaluation and close follow-up of cardiac morphology and function. Indeed, multi-disciplinary evaluation based on genotype-phenotype correlations of nMFS cases is essential to finding out the best medical and surgical approach, predicting the relevant impact on patient prognosis, and adequately counseling their families.

Genotype-phenotype spectrum and prognosis of early-onset Marfan syndrome

BACKGROUND

Marfan syndrome is a genetic connective tissue disorder affecting skeletal, ocular, and cardiovascular organ systems. Previous research found that pathogenic variants clustered in exons 24-32 of fibrillin-1 (FBN1) gene result in more severe clinical phenotypes. Furthermore, genotype-phenotype correlation studies suggested that more severe cardiovascular phenotypes were related to variants held responsible for haploinsufficiency. Our objective was to analyze the differences in clinical manifestations and genotypes of individuals with early-onset Marfan syndrome and to assess their impact on management strategies.

METHODS

We analyzed clinical and genetic data of a new patient with early-onset Marfan syndrome together with 51 previously reported ones in the PubMed database between 1991 and 2022.

RESULTS

Analysis showed 94% (49/52) of pathogenic variants clustered in exons 24-32 of the FBN1. The most common skeletal features were arachnodactyly (98%), reduced elbow extension (48%), pectus deformity (40%), and scoliosis (39%). Haploinsufficiency variants were reported as having poor outcome in 87.5% of the cases. Among patients carrying variants that substitute a cysteine for another amino acid and those that do not change cysteine content, cardiac intervention was found to be associated with a better outcome (p = 0.035 vs. p = 0.002). Variants that create an extra cysteine residue were found to be associated with a higher risk of ectopia lentis. Additionally, children up to 36-months-old were more often reported as still alive at the time of publication compared to newborns (p < 0.01).

CONCLUSIONS

Our findings have implications for prognosis, because different genotype groups and their resulting phenotype may require personalized care and management.