[Clinical phenotype and genetic analysis of six Chinese patients affected with Acromicric dysplasia due to variants of FBN1 gene]

Abstract

Objective: To retrospectively analyze the clinical and genetic characteristics of six patients with Acromicric dysplasia due to variants of the FBN1 gene.

Methods: Six patients who had visited the Affiliated Hospital of Qingdao University between February 2018 and October 2020 were selected as the study subjects. Clinical data of the patients were collected. High-throughput sequencing was carried out. And candidate variants were verified by Sanger sequencing.

Results: All of the six patients had presented with severe short stature (< 3s), brachydactyly, short and broad hands and feet. Other manifestations included joint stiffness, facial dysmorphism, delayed bone age, liver enlargement, coracoid femoral head, and lumbar lordosis. Genetic testing revealed that all had harbored heterozygous variants of the FBN1 gene. Patient 1 had harbored a c.5183C>T (p.A1728V) missense variant in exon 42, which had derived from his father (patient 2). Patient 3 had harbored a c.5284G>A (p.G1762S) missense variant in exon 43, which had derived from her mother (patient 4). Patient 5 had harbored a c.5156G>T (p.C1719F) missense variant in exon 42, which was de novo in origin. Patient 6 had harbored a c.5272G>T (p.D1758Y) missense variant in exon 43, which was also de novo in origin. The variants carried by patients 1, 3 and 6 were known to be pathogenic. Based on the guidelines from the American College of Medical Genetics and Genomics (ACMG), the FBN1: c.5156G>T was rated as a pathogenic variant (PS2+PM1+PM2_Supporting +PM5+PP3).

Conclusion: All of the six patients had severe short stature and a variety of other clinical manifestations, which may be attributed to the variants of the FBN1 gene.