Classical-like Ehlers-Danlos Syndrome · clEDS

Description

Classical-like Ehlers-Danlos syndrome is a rare heritable connective tissue disorder caused by complete deficiency of tenascin-X. Biallelic loss-of-function variants in TNXB abolish the tenascin-X glycoprotein, which contributes to the architecture of collagen-rich extracellular matrix. Inheritance is autosomal recessive, distinguishing it from classical EDS. Heterozygous carriers may show mild joint hypermobility but do not have the full phenotype. Prevalence is not well established and the condition is considered rare; fewer than several hundred molecularly confirmed cases have been published.

The 2017 international classification, published by Malfait and colleagues in the American Journal of Medical Genetics Part C, defines classical-like EDS clinically by skin hyperextensibility with velvety skin texture, generalized joint hypermobility with or without recurrent dislocations, and easy bruising or spontaneous ecchymoses. The skin overlap with classical EDS is substantial, with one important difference: atrophic scars are typically absent in classical-like EDS, which separates the phenotype from cEDS at the bedside. Foot deformities, edema in the legs without cardiovascular cause, mild proximal and distal muscle weakness, axonal polyneuropathy on electrophysiology, and vaginal, uterine, or rectal prolapse have been reported. A subset of people present with features overlapping vascular EDS, including spontaneous hollow organ rupture; this subset carries higher morbidity.

Genetic confirmation requires demonstration of biallelic TNXB pathogenic variants and absence of tenascin-X protein on serum or fibroblast assay. The TNXB locus is genomically complex. The pseudogene TNXA shares high sequence identity with the 3 prime end of TNXB and produces gene-conversion artifacts that confound short-read sequencing. Accurate diagnosis requires TNXB-specific approaches, including long-range PCR, multiplex ligation-dependent probe amplification, long-read sequencing, or serum tenascin-X immunoassay. Standard exome panels can miss the diagnosis without these adjustments.

A separate condition, contiguous gene deletion syndrome involving CYP21A2 and TNXB, can produce congenital adrenal hyperplasia together with classical-like EDS features and is identified through complementary endocrine workup.

Treatments to date

There is no disease-modifying therapy for classical-like EDS. Care is supportive and follows the principles applied across the heritable connective tissue disorders.

Skin protection and careful wound care reduce injury burden. Surgical wound closure follows the same tissue-handling principles used in classical EDS, including tension-free closure and prolonged retention of sutures, even though atrophic scarring is less prominent. Physical therapy oriented to joint stability, proprioception, and graded strengthening addresses musculoskeletal instability. Bracing supports unstable joints when needed.

Surveillance is individualized. People with features overlapping vascular EDS, including arterial or hollow organ rupture in the personal or family history, warrant vascular imaging and gastrointestinal evaluation. Pelvic floor symptoms and prolapse are evaluated by urogynecology. Polyneuropathy is followed by neurology. Genetic counseling addresses the autosomal recessive inheritance pattern, carrier screening for relatives, and reproductive options. No FDA-approved drug targets tenascin-X deficiency or the downstream matrix defect.