埃勒斯-當洛二氏症候群（英语：Ehlers-Danlos Syndrome，縮寫為 EDS），又稱皮膚彈力過度症（英语：Cutis hyperelastica）、鬆皮症、先天性結締組織異常症候群，是一種遺傳疾病，因膠原蛋白（第一型或第三型）生成的缺陷，造成結締組織異常而產生。特徵是會使得病人身上部份肌肉與關節組織，逐漸變得異常柔軟、有彈性，之後漸漸鬆弛。
這個病症首先由丹麥醫師愛德華·埃勒斯（Edvard Ehlers）與法國醫師昂利-亞歷山大·當洛（Henri-Alexandre Danlos），在二十世紀初時所確認，因此而命名。
||Affects 1 in 10,000 to 15,000 and is caused by an autosomal dominant or autosomal recessive mechanism. Mutations in either of two separate genes (which are also involved in Vascular EDS and Tenascin-X deficiency EDS, respectively) may lead to this variant. Hypermobility of varying degrees is the hallmark of this type, with less severe skin manifestations.
||types 1 & 2
||Affects approximately 1 in 20,000 to 50,000 people. It is caused by autosomal dominant mechanism and affects type-V collagen, as well as type I. Type 1 typically presents with severe skin involvement, and type 2 presents with mild to moderate skin involvement.
||COL5A1, COL5A2, COL1A1
||Is an autosomal dominant defect in the type-III collagen synthesis; affecting approximately 1 in 100,000 to 250,000 people. The vascular type is considered one of the more serious forms of Ehlers–Danlos syndrome because blood vessels and organs are more prone to tearing (rupture). Many patients with EDS type 4 express a characteristic facial appearance (large eyes, small chin, thin nose and lips, lobeless ears), have a small stature with a slim build, and typically have thin, pale, translucent skin (veins can usually be seen on the chest and abdomen) with very easy bruising and propensity to develop ecchymoses. About one in four people with vascular type EDS develop a significant health problem by age 20 and more than 80 percent develop life-threatening complications by age 40.
||Is an autosomal recessive defect due to deficiency of an enzyme called lysyl hydroxylase; it is very rare, with fewer than 60 cases reported. The kyphoscoliosis type is characterised by progressive curvature of the spine (scoliosis), fragile eyes, and severe muscle weakness.
||types 7A & B
||Is also very rare, with about 30 cases reported. It affects type-I collagen. The arthrochalasia type is characterised by very loose joints and dislocations involving both hips.
||Also very rare, with about 10 cases reported. The dermatosparaxis type is characterised by extremely fragile and sagging skin.