Infantile systemic hyalinosis: a case report with a novel mutation

Effect of Paediatric Rehabilitation in Infantile Systemic Hyalinosis: A Case Report

Infantile systemic hyalinosis (ISH) is a very rare autosomal recessive disorder, which is characterized by a systemic build-up of hyaline material that causes extensive tissue destruction and functional impairment. The signs of this debilitating illness, which can involve organs, skin anomalies, and joint contractures, frequently appear in infancy. The paucity of available research on ISH emphasizes the need for all-encompassing management approaches to address the wide range of symptoms and enhance the overall quality of life for impacted babies. The interdisciplinary approach to ISH highlights the need for physiotherapy as a crucial element, with an emphasis on addressing the motor and developmental problems linked to the illness. Improving mobility and functional independence in newborns with ISH is facilitated by therapeutic exercises designed specifically for their needs. Here, we present a case of a six-month-old male child who visited a tertiary care center with complaints of minimal movements of all four limbs since birth with the inability to hold the neck. On examination, it was found that there were low-set ears with popular rashes and contractures over distal joints. Electromyography (EMG) and nerve conduction velocity (NCV) were done, which had abnormal findings suggestive of myopathy. On skin biopsy, it was confirmed that the child was suffering from ISH. Thus, the patient was referred to a physiotherapist. After six weeks of physiotherapy sessions, it was found that early and consistent physiotherapy interventions have been linked to a decrease in joint stiffness-related pain and discomfort, improving the affected infants' general comfort. Furthermore, physiotherapy interventions have a crucial role in supporting adaptive methods to get around physical restrictions, making it easier for infants with ISH to reach developmental milestones that could otherwise be difficult. Although there is little research on the effects of physical therapy on infants with ISH, new data indicate that a proactive, tailored physical therapy program can greatly enhance the functional ability of impacted children, improve their overall quality of life, and avert further problems. It is crucial to incorporate physiotherapy into the comprehensive care of infants diagnosed with ISH. This highlights the significance of timely diagnosis, interdisciplinary cooperation, and continuous research aimed at improving and optimizing physiotherapeutic therapies for this uncommon and crippling genetic illness.

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.

Protein-losing enteropathy and joint contractures caused by a novel homozygous ANTXR2 mutation

Infantile systemic hyalinosis (ISH) is a rare autosomal recessive disorder and an allelic form of hyaline fibromatosis syndrome that is caused by mutations in the ANTRX2 gene encoding the transmembrane anthrax toxin receptor 2. Its main features include characteristic skin lesions, joint contractures, persistent diarrhea, and failure to thrive due to accumulation of hyaline material in multiple organs. The resulting severe malnutrition can cause death in early infancy. Because of its rarity and high fatality rate, timely diagnosis is difficult and ISH may be underdiagnosed. In this report, we describe a 10-month-old male with severe protein-losing enteropathy, skin lesions, and painful joint contractures, diagnosed with ISH based on skin his-topathology and identification of a novel homozygous ANTRX2 mutation, c.1127_1128delTG (p.V376Gfs*14). While its clinical outcome is poor without curative treatment, establishing a diagnosis of ISH starting from clinical suspicion to molecular analysis is important for appropriate medical management and for risk and carrier assessment of family members.

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: Report of two severe cases from Saudi Arabia and review of the literature

Infantile systemic hyalinosis (ISH) (OMIM 228600) is a rare fatal autosomal recessive disorder characterized by extensive deposition of hyaline material in many tissues. Consanguinity has been recorded in many cases. Herein we present two new Saudi cases with review of the literature. Our first proband was a 9 month-old male who was the first baby for parents descended from a closed consanguineous pedigree. The second proband was a 13 month-old male who was the first baby for consanguineous parents (3(rd) C). Both cases presented with bilateral painful limited limb movement with joints contractures, low birth weight (< P5), severe generalized stiff skin, hyper-pigmented skin over bony prominences, fleshy perianal masses and gingival hypertrophy. The first child died at 18(th) month as a result of recurrent chest infections. The second proband showed a severe progressive course of joint contractures, and died at 19(th) month because of failure to thrive and recurrent infections. Although the clinical features of ISH are characteristic, the disease is under/miss diagnosed. The role of consanguinity needed to be highlighted to the community. Careful clinical examination and molecular diagnosis will be helpful for genetic counseling, prenatal diagnosis and early treatment.

Infantile systemic hyalinosis in identical twins

Infantile systemic hyalinosis (ISH) is a rare disorder belonging to the heterogeneous group of genetic fibromatoses. It is a rare, progressive, fatal autosomal recessive condition characterized by widespread deposition of hyaline material in many tissues caused by mutations in the anthrax toxin receptor 2 gene - ANTXR2. It presents hyperpigmented skin over bony prominences. Characteristic purplish patches develop over the medial and lateral malleoli of the ankles, the metacarpophalangeal joints, spine and elbows, with progressive joint contractures, osteopenia, skin abnormalities and chronic severe pain. The present case reports the occurrence of infantile systemic hyalinosis in twin brothers five months of age who had come for early intervention for joint contractures representing characteristic brownish patches over bony prominences. ISH cases reported until this date have been less than 20 and the present case is unique in nature since this is the first time ISH is reported in twins globally and the symptoms have been identified at an early age.

Treatment of Massive Labial and Gingival Hypertrophy in a Patient With Infantile Systemic Hyalinosis-A Case Report

Infantile systemic hyalinosis (ISH) is a rare autosomal recessive disorder caused by a mutation in the ANTXR2 gene encoding a transmembranous protein involved in endothelial development. The ANTXR2 (also known as CMG2) locus is on chromosome 4q21. ISH is a common disorder in children of consanguineous parents in Arab countries. Symptoms of ISH manifest within the first months of life as progressive painful joint contractures and edema, hyperpigmentation of the skin, cutaneous nodules, persistent diarrhea with protein-losing enteropathy, and recurrent infections. Children affected by ISH often die undiagnosed in infancy. Histopathologic examination shows hyaline deposits in the skin, skeletal muscles, cardiac muscle, lymph nodes, adrenal glands, gastrointestinal tract, thyroid, and spleen. Hyaline deposits are the result of leakage of plasma components to the perivascular space owing to defective endothelial morphogenesis. ISH manifests most often in the facial region. Patients develop hypertrophy of labial and buccal tissues and massive gingival overgrowths, which impair oral food intake and maintenance of satisfactory oral hygiene. The differential diagnosis of ISH should consider juvenile systemic hyalinosis (an allelic variant of ISH), Winchester syndrome, systemic fibromatosis, stiff skin syndrome, lipoid proteinosis, mucopolysaccharidosis, sphingolipidosis, and mucolipidosis. This report describes a case of massive labial and gingival hypertrophy in a 6-year-old boy with ISH.

Therapeutic potential of capillary morphogenesis gene 2 extracellular vWA domain in tumour‑related angiogenesis

Capillary morphogenesis gene 2 (CMG2) is a receptor of anthrax toxin and plays an important role in angiogenesis. It has been shown to be involved in the cell adhesion and motility of various cell types, including epithelia and endothelia. The present study aimed to examine the therapeutic potential of targeting CMG2 to prevent tumour‑related new vasculature. The full-length coding sequence of the human CMG2 gene and different fragments of the CMG2 vWA domain were amplified and constructed into a mammalian expression plasmid vector. The effect of CMG2 and its vWA domain on endothelial cells and angiogenesis was assessed using relevant in vitro, ex vivo and in vivo models. The overexpression of CMG2 enhanced the adhesion of endothelial cells to extracellular matrix, but was negatively associated with cell migration. Overexpression of CMG2 and the vWA domain fragments inhibited the tubule formation and migration of endothelial cells. Small peptides based on the amino acid sequence of the CMG2 vWA domain fragments potently inhibited in vitro tubule formation and ex vivo angiogenesis. One of the polypeptides, LG20, showed an inhibitory effect on in vivo tumour growth of cancer cells which were co-inoculated with the vascular endothelial cells. CMG2 is a potential target for treating tumour‑related angiogenesis. The polypeptides based on the CMG2 vWA domain can potently inhibit in vitro and ex vivo angiogenesis, which may contribute to the inhibitory effect on in vivo tumour growth. Further investigations are required to shed light on the machinery and may provide a novel therapeutic approach for inhibition of angiogenesis in cancer management.