Infantile systemic hyalinosis in an Iranian family with a mutation in the CMG2/ANTXR2 gene

Hyaline fibromatosis syndrome with a novel 4.41-kb deletion in ANTXR2 gene: A case report and literature review

BACKGROUND

Hyaline fibromatosis syndrome is a rare autosomal recessive disorder with ANTXR2 mutations characterised by the accumulation of hyaline substances in tissues. We present a case with the severe form-infantile systemic hyalinosis (ISH)-with long survival and review the literature.

METHODS AND RESULTS

Trio-exome sequencing revealed compound heterozygous mutations, including a novel 4.41 kb deletion on 4q21.21 and the previously reported c.1294C > T mutation, in the ANTXR2 gene. He was diagnosed with ISH and treated symptomatically. After follow-ups until 4 years of age, his recurrent respiratory infections and diarrhoea improved after one severe diarrhoea attack treated with intravenous gamma globulin. He is now awaiting surgical excision of gingival hypertrophy and joint contractures.

CONCLUSION

The novel gross deletion in ANTXR2 enriches the genetic mutation spectrum of hyaline fibromatosis syndrome. The manifestation of decreased foetal movement, acute-infection attack or intravenous gamma globulin treatment may be associated with hyaline fibromatosis syndrome. A review of 116 reported cases reveals that missense mutations in the vWA domain are associated with joint symptoms, respiratory tract infection and diarrhoea, while frameshift mutations are associated with facial deformities and speech delays. We have enriched the current knowledge of the clinical manifestations and genetic mutation spectrum of HFS.

Hyaline fibromatosis syndrome: A case report

Hyaline fibromatosis syndrome (HFS) is a rare monogenic disease inherited in an autosomal recessive pattern and characterized by hyaline deposits on the skin, mucosa, and multiple organs; osteoporosis; and joint contractures. This progressive condition is caused by mutations in the gene encoding the anthrax toxin receptor 2 protein (ANTXR2). HFS is a disabling disease, and patients suffer from progressive pain and disfiguring symptoms. There are few published case reports detailing oral findings in patients with this condition. The present case report describes a 4-year-old female patient who showed severe manifestations of HFS, emphasizing the oral manifestations, the histopathologic aspects of HFS, the molecular pathogenesis, and the interdisciplinary management of patients affected by this condition.

Hyaline fibromatosis syndrome: Clinical update and phenotype-genotype correlations

Hyaline fibromatosis syndrome (HFS) is the unifying term for infantile systemic hyalinosis and juvenile hyaline fibromatosis. HFS is a rare autosomal recessive disorder of the connective tissue caused by mutations in the gene for anthrax toxin receptor-2 (ANTXR2). It is characterized by abnormal growth of hyalinized fibrous tissue with cutaneous, mucosal, osteoarticular, and systemic involvement. We reviewed the 84 published cases and their molecular findings, aiming to gain insight into the clinical features, prognostic factors, and phenotype-genotype correlations. Extreme pain at minimal handling in a newborn is the presentation pattern most frequently seen in grade 4 patients (life-limiting disease). Gingival hypertrophy and subcutaneous nodules are some of the disease hallmarks. Though painful joint stiffness and contractures are almost universal, weakness and hypotonia may also be present. Causes of death are intractable diarrhea, recurrent infections, and organ failure. Median age of death of grade 4 cases is 15.0 months (p25-p75: 9.5-24.0). This review provides evidence to reinforce the previous hypothesis that missense mutations in exons 1-12 and mutations leading to a premature stop codon lead to the severe form of the disease, while missense pathogenic variants in exons 13-17 lead to the mild form of the disease. Multidisciplinary team approach is recommended.

Two novel mutations in the ANTXR2 gene in a Chinese patient suffering from hyaline fibromatosis syndrome: A case report

Hyaline fibromatosis syndrome (HFS; MIM 228600) is a rare autosomal recessive disorder characterized by the abnormal growth of hyalinized fibrous tissue at subcutaneous regions on the scalp, ears and neck. The disease is caused by either a homozygous or compound heterozygous mutation of the anthrax toxin receptor 2 (ANTXR2) gene. The present study describes a patient with HFS confirmed by clinical examination as well as histopathological and genetic analyses. Numerous painless and variable‑sized subcutaneous nodules were observed on the scalp, ear, trunk and four extremities of the patient. With increasing age, the number and size of the nodules gradually increased in the patient. The patient additionally presented with severe gingival thickening and developed pearly papules on the ears, back and penis foreskin. Biopsies of ear nodules revealed that the tumor was located in the dermis, and no marked alterations were observed in the epidermis compared with healthy patients. Spindle‑shaped or round tumor cells were revealed to be immersed in the eosinophilic hyaline ground substance. Furthermore, a skeletal X‑ray of the patient revealed multiple low‑density imaging on the right distal humerus. Compound heterozygous mutations in the ANTXR2 gene were identified in the patient: c.470_472del in exon 5 and c.1073 delC in exon 13. c.470_472del were revealed to be inherited from his mother and father, respectively. These two mutations, c.470_472del and c.1073 delC, to the best of our knowledge, have not previously been identified. Identification of the mutations in ANTXR2 may make prenatal diagnosis of HFS possible during future pregnancies.

The genetic basis of hyaline fibromatosis syndrome in patients from a consanguineous background: a case series

BACKGROUND

Hyaline fibromatosis syndrome (HFS) is a rare heritable multi-systemic disorder with significant dermatologic manifestations. It is caused by mutations in ANTXR2, which encodes a transmembrane receptor involved in collagen VI regulation in the extracellular matrix. Over 40 mutations in the ANTXR2 gene have been associated with cases of HFS. Variable severity of the disorder in different patients has been proposed to be related to the specific mutations in these patients and their location within the gene.

CASE PRESENTATION

In this report, we describe four cases of HFS from consanguineous backgrounds. Genetic analysis identified a novel homozygous frameshift deletion c.969del (p.Ile323Metfs*14) in one case, the previously reported mutation c.134 T > C (p.Leu45Pro) in another case, and the recurrent homozygous frameshift mutation c.1073dup (p.Ala359Cysfs*13) in two cases. The epidemiology of this latter mutation is of particular interest, as it is a candidate for inhibition of nonsense-mediated mRNA decay. Haplotype analysis was performed to determine the origin of this mutation in this consanguineous cohort, which suggested that it may develop sporadically in different populations.

CONCLUSIONS

This information provides insights on genotype-phenotype correlations, identifies a previously unreported mutation in ANTXR2, and improves the understanding of a recurrent mutation in HFS.

Diagnosis implications of the whole genome sequencing in a large Lebanese family with hyaline fibromatosis syndrome

BACKGROUND

Hyaline fibromatosis syndrome (HFS) is a recently introduced alternative term for two disorders that were previously known as juvenile hyaline fibromatosis (JHF) and infantile systemic hyalinosis (ISH). These two variants are secondary to mutations in the anthrax toxin receptor 2 gene (ANTXR2) located on chromosome 4q21. The main clinical features of both entities include papular and/or nodular skin lesions, gingival hyperplasia, joint contractures and osteolytic bone lesions that appear in the first few years of life, and the syndrome typically progresses with the appearance of new lesions.

METHODS

We describe five Lebanese patients from one family, aged between 28 and 58 years, and presenting with nodular and papular skin lesions, gingival hyperplasia, joint contractures and bone lesions. Because of the particular clinical features and the absence of a clinical diagnosis, Whole Genome Sequencing (WGS) was carried out on DNA samples from the proband and his parents.

RESULTS

A mutation in ANTXR2 (p. Gly116Val) that yielded a diagnosis of HFS was noted.

CONCLUSIONS

The main goal of this paper is to add to the knowledge related to the clinical and radiographic aspects of HFS in adulthood and to show the importance of Next-Generation Sequencing (NGS) techniques in resolving such puzzling cases.

Infantile Systemic Hyalinosis: Novel Founder Mutation in the Initiation Codon among "Malis (Farmers)" in Jodhpur

Infantile systemic hyalinosis (OMIM 236490) is a progressive autosomal recessive disorder characterized by widespread deposition of hyaline material in many tissues leading to multiple subcutaneous skin nodules, gingival hypertrophy and joint contractures. The authors describe five children from four unrelated families, from the "mali (farmer)" community in Jodhpur, with the disorder. All of them had classical clinical features, and four died from severe infections between age of 7 mo to 3 y. Two affected children had the same, but novel mutation in the initiation codon, in homozygous form c.1 A > G; p. M1? in capillary morphogenesis protein-2 (CMG2), or ANTXR2 gene on chromosome 4q21.21. The other two parents had the same mutation in heterozygous form. It is likely that this is a founder mutation in this community.