Ehlers-Danlos syndrome (EDS) is the name given to a group of connective tissue disorders caused by mutations in genes such as COL1A1, COL1A2, COL3A1, COL5A1, COL5A2, and COL12A1 that provide instructions for making different types of collagen protein components, or genes such as ADAMTS2, FKBP14, PLOD1, and TNXB that give instructions for proteins associated with collagen, or proteins that help in the synthesis of new collagen proteins.
Depending on the gene that is mutated, there are 13 types of EDS. Although in the majority of cases EDS is inherited from the parents, in rare cases, it can occur without any family history and due to new mutations occurring during development.
EDS may be inherited in one of two ways: autosomal dominant and autosomal recessive. Autosomes are non-sex chromosomes. There are 22 pairs of autosomal chromosomes and one pair of sex chromosomes in humans; XX in females and XY in males.
Autosomal dominant inheritance
Classical, vascular, arthrochalasia, periodontal, and hypermobile EDS are inherited in an autosomal dominant pattern. Autosomal dominant inheritance is when one of the two copies of a mutated gene is sufficient to cause the disease. The mutant gene is inherited from one of the parents who also is affected by the disease.
If a person is affected by a type of EDS that follows an autosomal dominant inheritance pattern, they have a 50% chance of passing on the disease to their child.
Autosomal recessive inheritance
Classical-like, cardiac-valvular, dermatosparaxis, kyphoscoliotic, spondylodysplastic, musculocontractural, and brittle cornea syndrome EDSÂ are inherited in an autosomal recessive pattern. In this case, both copies of a gene are mutated in the affected individual with one mutant copy being inherited from each parent.
A child born to parents who carry the same autosomal recessive mutation has a 25% chance of inheriting the mutant gene from both parents and developing the disease. They have a 50% chance of inheriting a single mutated copy and being a carrier of the disease. Also, they have a 25% chance of inheriting two healthy copies of the gene from each parent and not having EDS.
Myopathic EDS mutations
Myopathic EDS can be inherited in either an autosomal dominant or autosomal recessive pattern. Myopathic EDS is mostly caused by mutations in the COL12A1 gene, which has the instructions for making the type 12 collagen.
In some cases, myopathic EDS is caused by mutations in the FKBP14 gene, which provides instructions for the so-called FK506-binding protein-14. This protein helps in folding newly synthesized proteins including collagen into a functional conformation (shape).
Last updated: Oct. 16, 2019
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