From OMIM
The Loeys-Dietz syndrome (LDS) is an autosomal dominant aortic aneurysm syndrome with widespread systemic involvement. As defined by Loeys et al. (2006), the disorder is characterized by the triad of arterial tortuosity and aneurysms, hypertelorism, and bifid uvula or cleft palate. Some patients have craniofacial involvement consisting of cleft palate, craniosynostosis, or hypertelorism. Bifid uvula may also be present. The natural history is characterized by aggressive arterial aneurysms and a high rate of pregnancy-related complications. LDS is also associated with immunologic-related disorders: approximately one-third of affected individuals exhibit food allergies, in contrast to a prevalence of 6 to 8% in the general population, and LDS patients have an increased prevalence of asthma, rhinitis, and eczema (summary by MacCarrick et al., 2014). Nomenclature In initial reports, LDS patients, defined as those with mutations in TGFBR1 or TGFBR2, were stratified into 2 types, depending on severity of craniofacial features (type 1) or cutaneous features (type 2) (MacCarrick et al., 2014). Given that vascular disease is the major concern in LDS irrespective of the severity of systemic features, a revised nosology was proposed with sequential numbering corresponding to the gene mutant in each group (see below). Genetic Heterogeneity of Loeys-Dietz Syndrome LDS1 is caused by mutation in the TGFBR1 gene. LDS2 (610168) is caused by mutation in the TGFBR2 gene (190182). LDS3 (613795), which is associated with early-onset osteoarthritis, is caused by mutation in the SMAD3 gene (603109). LDS4 (614816) is caused by mutation in the TGFB2 gene (190220). LDS5 (615582) is caused by mutation in the TGFB3 gene (190230). LDS6 (619656) is caused by mutation in the SMAD2 gene (601366). Reviews MacCarrick et al. (2014) provided a review of LDS, stating that there are no specific clinical criteria for the diagnosis, which is confirmed by molecular testing. They proposed that mutation in any of the 4 genes, TGFBR1, TGFBR2, SMAD3, or TGFB2, in combination with arterial aneurysm or dissection or a family history of documented LDS, should be sufficient to establish the diagnosis. The authors noted that rapidly progressive aortic aneurysmal disease is a distinct feature of LDS, and they discussed management strategies for cardiovascular issues as well as other complications of LDS. Schepers et al. (2018) reviewed the clinical manifestations of LDS associated with mutation in the TRFBR1/2, TGFB1/2, and SMAD2/3 genes, concluding that the LDS phenotype represents a broad spectrum that is emerging as more patients are reported. They suggested genetic testing of the LDS genes be performed in the following scenarios: patients with the typical clinical trial of hypertelorism, cleft palate/bifid uvula and arterial tortuosity/aneurysm; early-onset aortic aneurysm with variable combination of other features including arachnodactyly, camptodactyly, clubfeet, any type of craniosynostosis, blue sclerae, thin skin with atrophic scars, easy bruising, joint hypermobility, bicuspid aortic valve, patent ductus arteriosus, atrial and ventricular septal defects; sporadic young probands with aortic root dilatation/dissection; families with autosomal dominant thoracic aortic aneurysms, especially those families with early-onset aortic/arterial dissection or aortic disease beyond the aortic root, including cerebral arteries; patients with a Marfan syndrome (MFS; 154700)-like phenotype, especially those without ectopia lentis, but with aortic and skeletal features not fulfilling the MFS diagnostic criteria; and patients with clinical features reminiscent of vascular Ehlers-Danlos syndrome (130050), including thin skin with atrophic scars, easy bruising, and joint hypermobility, who have normal type III collagen biochemistry and/or normal COL3A1 (120180) genetic testing. Diagnosis Schepers et al. (2018) noted that no formal diagnostic criteria had been developed for LDS, but stated that the diagnosis is established in individuals with a heterozygous pathogenic variant in SMAD2, SMAD3, TGFB2, TGFB3, TGFBR1, or TGFBR2 who exhibit either aortic root enlargement (defined as an aortic root z-score greater than or equal to 2.0) or type A dissection, or compatible systemic features including characteristic craniofacial, skeletal, cutaneous, and/or vascular manifestations found in combination. Special emphasis should be given to arterial tortuosity, particularly of the head and neck vessels, and to aneurysms or dissections involving medium-to-large muscular arteries throughout the arterial tree.  http://www.omim.org/entry/609192

From MedlinePlus Genetics
People with Loeys-Dietz syndrome may bruise easily and develop abnormal scars after wound healing. The skin is frequently described as translucent, often with stretch marks (striae) and visible underlying veins. Some individuals with Loeys-Dietz syndrome develop an abnormal accumulation of air in the chest cavity that can result in the collapse of a lung (spontaneous pneumothorax) or a protrusion of organs through gaps in muscles (hernias). Other characteristic features include widely spaced eyes (hypertelorism), eyes that do not point in the same direction (strabismus), a split in the soft flap of tissue that hangs from the back of the mouth (bifid uvula), and an opening in the roof of the mouth (cleft palate).

Individuals with Loeys-Dietz syndrome often have skeletal problems including premature fusion of the skull bones (craniosynostosis), an abnormal side-to-side curvature of the spine (scoliosis), either a sunken chest (pectus excavatum) or a protruding chest (pectus carinatum), an inward- and upward-turning foot (clubfoot), flat feet (pes planus), or elongated limbs with joint deformities called contractures that restrict the movement of certain joints. A membrane called the dura, which surrounds the brain and spinal cord, can be abnormally enlarged (dural ectasia). In individuals with Loeys-Dietz syndrome, dural ectasia typically does not cause health problems. Malformation or instability of the spinal bones (vertebrae) in the neck is a common feature of Loeys-Dietz syndrome and can lead to injuries to the spinal cord. Some affected individuals have joint inflammation (osteoarthritis) that commonly affects the knees and the joints of the hands, wrists, and spine.

Loeys-Dietz syndrome is characterized by enlargement of the aorta, which is the large blood vessel that distributes blood from the heart to the rest of the body. The aorta can weaken and stretch, causing a bulge in the blood vessel wall (an aneurysm). Stretching of the aorta may also lead to a sudden tearing of the layers in the aorta wall (aortic dissection). People with Loeys-Dietz syndrome can also have aneurysms or dissections in arteries throughout the body and have arteries with abnormal twists and turns (arterial tortuosity).

There are five types of Loeys-Dietz syndrome, labelled types I through V, which are distinguished by their genetic cause. Regardless of the type, signs and symptoms of Loeys-Dietz syndrome can become apparent anytime from childhood through adulthood, and the severity is variable.

Individuals with Loeys-Dietz syndrome frequently develop immune system-related problems such as food allergies, asthma, or inflammatory disorders such as eczema or inflammatory bowel disease.

Loeys-Dietz syndrome is a disorder that affects the connective tissue in many parts of the body. Connective tissue provides strength and flexibility to structures such as bones, ligaments, muscles, and blood vessels.  https://medlineplus.gov/genetics/condition/loeys-dietz-syndrome