Abstract

BACKGROUND
Juvenile hyaline fibromatosis is a rare autosomal recessive disorder with unknown prevalence characterized by abnormal development of hyalinized fibrous tissue usually in the skin, mucosa, bone, and often the internal organs. Here, we report the case of a 7-year-old girl from a family with ANTXR2 mutation confirming JHF.
CASE REPORT
The girl presented with multiple painless soft-tissue swellings affecting the ears, forehead, and scalp. Excisional biopsies of the masses reported positive immunohistochemical staining for collagen type VI in the extracellular matrix area, which indicated collagen VI accumulation. Genetic analysis was performed using whole-exome sequencing. The variants were further validated using Sanger sequencing in trio-based approach. We identified a novel mutation, c.1273_1293delinsTCTTGTGGGTTTGGCT in exon 15 of ANTXR2 gene, leading to a frameshift of the amino acid from codon 425 to all the rest of the amino acid chain (p.Pro425Serfs). The change of an encoded protein interrupted lysosome-mediated degradation of collagen VI. This finding was compatible with her parents whose genetic tests were both positive for the same heterogenous deletion/insertion mutation. The patient was treated with surgical excision of the tumor masses, which had to be repeated several times due to recurrences.
CONCLUSIONS
This novel mutation in exon 15 of the ANTXR2 gene may help improve understanding of genotype-phenotype correlations for this syndrome and provide the basis for diagnostic testing. A multidisciplinary team approach including genetic molecular testing is required for an accurate diagnosis and management of JHF for conducting genetic counseling for affected families as a part of holistic management.

Keywords: Collagen Type VI; Hyalinosis, Systemic; Whole Exome Sequencing; ANTXR2 Protein, Human