| ā | Clinical manifestations |
| Upper airways | Facial coarseness, hypertelorism, sunken nasal dorsum, anteverted nostrils, thickened lips, gingival hyperplasia [19] and dental distortions. Swollen tongue, epiglottis, tonsils and adenoids [47], pharyngomalacia (anterior position of larynx [48]). |
| Lower airways | Expanded larynx and tracheobronchomalacia [49] (enlarged cartilage). Recurrent pneumonia and restrictive lung disease that results in lung failure, Obstructive Sleep Apnea and sudden death for central apnea [5]. Rhinitis, tonsillitis, laryngitis and otitis media [4, 47]. |
| Cardiac | Valvular disease, cardiomyopathy, right ventricular dysfunction and congestive heart failure [2, 27]. Coronary vessel flow impairment and cardiac ischemia [20, 50]. |
| Orthopedic-Bone Changes | Short neck, joints stiffness [47], odontoid instability [48], hypo plastic mandible, thoracic cage restriction for kyphoscoliosis [24]. Hip dysplasia, valgus knee, spinal cord compression and atlanto-axial instability [51, 52]. |
| Others | Mental retardation [14] and hyperactive, aggressive behavior [53]. Communicating hydrocephalus. Hearing loss [2], corneal opacities [54, 55]. Hepatosplenomegaly, umbilical and inguinal hernias [39, 40]. |
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