MedGen

Dyskeratosis congenita and related telomere biology disorders (DC/TBD) are caused by impaired telomere maintenance resulting in short or very short telomeres. The phenotypic spectrum of telomere biology disorders is broad and includes individuals with classic dyskeratosis congenita (DC) as well as those with very short telomeres and an isolated physical finding. Classic DC is characterized by a triad of dysplastic nails, lacy reticular pigmentation of the upper chest and/or neck, and oral leukoplakia, although this may not be present in all individuals. People with DC/TBD are at increased risk for progressive bone marrow failure (BMF), myelodysplastic syndrome or acute myelogenous leukemia, solid tumors (usually squamous cell carcinoma of the head/neck or anogenital cancer), and pulmonary fibrosis. Other findings can include eye abnormalities (epiphora, blepharitis, sparse eyelashes, ectropion, entropion, trichiasis), taurodontism, liver disease, gastrointestinal telangiectasias, and avascular necrosis of the hips or shoulders. Although most persons with DC/TBD have normal psychomotor development and normal neurologic function, significant developmental delay is present in both forms; additional findings include cerebellar hypoplasia (Hoyeraal Hreidarsson syndrome) and bilateral exudative retinopathy and intracranial calcifications (Revesz syndrome and Coats plus syndrome). Onset and progression of manifestations of DC/TBD vary: at the mild end of the spectrum are those who have only minimal physical findings with normal bone marrow function, and at the severe end are those who have the diagnostic triad and early-onset BMF. [from GeneReviews]

NKX2-1-related disorders range from benign hereditary chorea (BHC) to choreoathetosis, congenital hypothyroidism, and neonatal respiratory distress (also known as brain-lung-thyroid syndrome). Childhood-onset chorea, the hallmark of NKX2-1-related disorders, may or may not be associated with respiratory distress syndrome or congenital hypothyroidism. Chorea generally begins in early infancy or about age one year (most commonly) or in late childhood or adolescence, and progresses into the second decade after which it remains static or (rarely) remits. Pulmonary disease, the second most common manifestation, can include respiratory distress syndrome in neonates, interstitial lung disease in young children, and pulmonary fibrosis in older persons. The risk for pulmonary carcinoma is increased in young adults with an NKX2-1-related disorder. Thyroid dysfunction, the result of dysembryogenesis, can present as congenital hypothyroidism or compensated hypothyroidism. The risk for thyroid cancer is unknown and may not be increased. In one review, 50% of affected individuals had the full brain-lung-thyroid syndrome, 30% had involvement of brain and thyroid only, and 13% had isolated chorea only. [from GeneReviews]

Diffuse panbronchiolitis (DPB) is a rare chronic inflammatory obstructive pulmonary disease primarily affecting the respiratory bronchioles. 'Diffuse' refers to the distribution of the lesions throughout both lungs, and 'pan-' refers to the involvement of inflammation in all layers of the respiratory bronchioles. Onset of the disorder occurs in the second to fifth decade of life, and is clinically manifest by chronic cough, exertional dyspnea, and sputum production. Most patients also have chronic paranasal sinusitis. If untreated, the disorder progresses to bronchiectasis, respiratory failure, and death (summary by Poletti et al., 2006). [from OMIM]

Goodpasture syndrome, also known as anti-GBM disease, is a rare autoimmune disease consisting of alveolar hemorrhage and glomerulonephritis secondary to circulating antiglomerular basement membrane (anti-GBM) antibodies. Anti-GBM antibodies are directed against an antigen intrinsic to the alpha-3 chain of type IV collagen (COL4A3; 120070) that is expressed in the GBMs of the glomerular capillary loops and the basal membrane of the pulmonary alveoli. Goodpasture syndrome is suspected in patients with hemoptysis and hematuria and is confirmed by the presence of anti-GBM antibodies in renal biopsy specimens and serum. Patients with human leukocyte antigen HLA-DR15 and HLA-DR4 are susceptible to the development of Goodpasture syndrome. Reported cases of familial Goodpasture syndrome are extremely rare (summary by Angioi et al., 2017). [from OMIM]

Interstitial lung disease (ILD) comprises a heterogeneous group of rare diseases affecting the distal part of the lung and characterized by a progressive remodeling of the alveolar interstitium. The manifestations form a spectrum ranging from idiopathic interstitial pneumonia (IIP) or pneumonitis to the more severe idiopathic pulmonary fibrosis (IPF). IPF is associated with an increased risk of developing lung cancer, which occurs in a subset of patients with ILD. Clinical features of ILD include dyspnea, clubbing of the fingers, and restrictive lung capacity. Imaging typically shows ground glass opacities and inter- and intraseptal thickening, while histologic studies usually show a pattern consistent with 'usual interstitial pneumonia' (UIP) (summary by Nathan et al., 2016, Doubkova et al., 2019). Genetic Heterogeneity of Interstitial Lung Disease See also ILD2 (178500), caused by mutation in the SFTPA2 gene (178642) on chromosome 10q22. [from OMIM]

Recurrent respiratory infections and failure to thrive with or without diarrhea (RIFTD) is characterized by neonatal onset of chronic cough, episodic wheezing, recurrent lower respiratory tract infections, chronic diarrhea, and failure to thrive. Despite the resemblance to cystic fibrosis (CF; 219700), these patients have normal sweat chloride and pancreatic elastase tests (Bertoli-Avella et al., 2022). [from OMIM]

Crackles are discontinuous, explosive, and nonmusical adventitious lung sounds normally heard in inspiration and sometimes during expiration. Crackles are usually classified as fine and coarse crackles based on their duration, loudness, pitch, timing in the respiratory cycle, and relationship to coughing and changing body position. [from HPO]