Predictors of low bone density and fracture risk in Loeys-Dietz syndrome.

PURPOSE: Loeys-Dietz syndrome (LDS) is a connective tissue disorder affecting multiple organ systems, including bone. METHODS: We defined the bone phenotype and clinical predictors of low bone density and fracture risk in 77 patients with LDS type 1 to type 5. RESULTS: Patients with LDS had dual-energy x-ray absorptiometry (DXA) Z-scores significantly < 0, and 50% of children and 9% of adults had Z-scores < -2. Sixty percent of patients had ≥1 fracture, and 24% of patients with spinal x-rays scans showed spinal compression fractures. Lower body mass index, asthma, male sex and eosinophilic gastrointestinal disease were correlated with lower DXA Z-scores. The count of 5 LDS-associated skeletal features (scoliosis, pes planus, arachnodactyly, spondylolisthesis, and camptodactyly) in patients with LDS was correlated with DXA Z-score. Adults with ≥1 skeletal features had DXA Z-scores significantly < 0, and children with >2 features had DXA Z-score significantly < -2. Bone turnover markers suggest accelerated bone resorption. Data from 5 patients treated with bisphosphonates suggest a beneficial effect. CONCLUSION: All LDS types are associated with reduced bone density and increased risk of fracture, which may be due to increased bone resorption. Clinical features can predict a subgroup of patients at highest risk of low bone density and fracture risk.

Audiologic and Otologic Clinical Manifestations of Loeys-Dietz Syndrome: A Heritable Connective Tissue Disorder.

OBJECTIVE: Loeys-Dietz syndrome (LDS) is a rare genetic connective tissue disorder resulting from TGF-ß signaling pathway defects and characterized by a wide spectrum of aortic aneurysm, arterial tortuosity, and various extravascular abnormalities. This study describes the audiologic, otologic, and craniofacial manifestations of LDS. STUDY DESIGN: Consecutive cross-sectional study. SETTING: Tertiary medical research institute. METHODS: Audiologic and clinical evaluations were conducted among 36 patients (mean ± SD age, 24 ± 17 years; 54% female) with genetically confirmed LDS. Cases were categorized into genetically based LDS types 1 to 4 (TGFBR1, TGFBR2, SMAD3, TGFB2, respectively). Audiometric characteristics included degree and type of hearing loss: subclinical, conductive, mixed, and sensorineural. RESULTS: LDS types 1 to 4 included 11, 13, 5, and 7 patients, respectively. In LDS-1, 27% had bilateral conductive hearing loss; 9%, unilateral mixed; and 36%, subclinical. In LDS-2, 38% had conductive hearing loss and 38% subclinical. In LDS-3 and LDS-4, 40% and 43% had bilateral sensorineural hearing loss, respectively. Degree of hearing loss ranged from mild to moderate. Bifid uvula was observed only in LDS-1 (55%) and LDS-2 (62%). Submucosal/hard cleft palates were primarily in LDS-1 and LDS-2. Posttympanostomy tympanic membrane perforations occurred in 45% (10/22 ears) of LDS-1 and LDS-2. There were 4 cases of cholesteatoma: 3 middle ear (LDS-1 and LDS-2) and 1 external ear canal (LDS-3). CONCLUSION: Conductive hearing loss, bifid uvula/cleft palate, and posttympanostomy tympanic membrane perforation are more common in LDS-1 and LDS-2 than LDS-3 and LDS-4, while sensorineural hearing loss was present only in LDS-3 and LDS-4. These LDS-associated key clinical presentations may facilitate an early diagnosis of LDS and thus prompt intervention to prevent related detrimental outcomes.