Alveolar capillary dysplasia
|Alveolar Capillary Dysplasia|
|Classification and external resources|
Alveolar capillary dysplasia (ACD, sometimes denoted ACDMPV when including misalignment of the pulmonary veins) is a type of diffuse developmental disorder of the lung. The other two diffuse developmental disorders are congenital acinar dysplasia and congenital alveolar dysplasia (CAD).
ACD or ACDMPV is the best studied diffuse developmental disorder. It is a very rare congenital malformation involving abnormal development of the capillary vascular system around the alveoli of the lungs. It is a rare cause of persistent pulmonary hypertension in infants. It also may be a rare cause of pulmonary hypoplasia.
Babies with ACD may appear normal at birth but within minutes or hours they develop respiratory distress with persistent pulmonary hypertension. ACD does not respond to standard therapies that resolve simple pulmonary hypertension. The lack of response is an important diagnostic clue.
Cause of ACD
Two broad types of genetic abnormality have been found to cause ACDMPV: (1) a mutation of the FOXF1 gene on chromosome 16, or (2) other genetic abnormalities such as deletions in areas of chromosome 16 that regulate the expression of the FOXF1 gene. New genetic abnormalities are being found regularly, but at present around 80-90% of infants with confirmed ACDMPV can be found to have one of these abnormalities. The genetic abnormalities responsible for ACDMPV in the remaining 10-20% of cases are currently being investigated including testing for deletions farther away from the FOXF1 gene on chromosome 16 and whole exome testing.
ACD is not detectable by prenatal imaging. However, some babies with ACD have associated congenital malformations that are detectable by imaging. The identification of genes involved in ACD offers the potential for prenatal testing and genetic counseling.
Most babies with ACD have normal Apgar scores at 1 and 5 minutes, but within minutes or hours present with hypoxia and upon investigation are found to have hypoxemia and pulmonary hypertension. Initial treatments address the hypoxia, usually beginning with supplemental oxygen and arrangements for urgent transport to a neonatal intensive care unit.
Therapies that have been tried to extend life include extracorporeal membrane oxygenation and nitric oxide. These are supportive therapies for persistent pulmonary hypertension; they do not treat the ACD. The objective of therapy is to keep the baby alive long enough to obtain a lung transplant.
Baylor College of Medicine in Houston, Texas has conducted ACD research since 2001.
Advance in experimental treatment
Several patients have survived with atypical or “patchy ACDMPV” long enough to receive lung transplants. According to a 2013 case series conducted by St. Louis Children’s Hospital, four ACDMPV patients (ages 4 months, 5 months, 9 months and 20 months of age at time of transplant) with atypical presentations of ACDMPV each underwent a successful bilateral lung transplantation (BLT). As stated in the case study, “If they survive to BLT, patients with ACDMPV can have successful outcomes” and the ACDMPV patients “are alive at last follow-up at 1, 8, 9 and 12 years of age” (as of May 2013).
According to the St. Louis Children's Hospital (the Level I pediatric trauma center and pediatric teaching hospital for the Washington University School of Medicine), which is noted worldwide for its record in pediatric pulmonary transplantation, a type of artificial lung device, the Quadrox, was used after ECMO as a bridge to a dual lung transplant in ten-month-old Eleni Scott of the St. Louis suburb of Florissant, Missouri, who after transplantation returned to her home. Doctors have said it is too early to presume it will continue to work here or work in other pediatric patients as an experiment, much less a successful, curative standard therapy, but the infant has survived thus far, meaning that there might be hope for sufferers of this rare condition. For more information, please see the link to the news release.
- Cater G, Thibeault DW, Beatty EC, Kilbride HW, Huntrakoon M (February 1989). "Misalignment of lung vessels and alveolar capillary dysplasia: a cause of persistent pulmonary hypertension". The Journal of Pediatrics. 114 (2): 293–300. doi:10.1016/S0022-3476(89)80800-5. PMID 2915290.
- Sirkin W, O'Hare BP, Cox PN, Perrin D, Cutz E, Silver MM (1997). "Alveolar capillary dysplasia: lung biopsy diagnosis, nitric oxide responsiveness, and bronchial generation count". Pediatric Pathology & Laboratory Medicine : Journal of the Society for Pediatric Pathology, Affiliated with the International Paediatric Pathology Association. 17 (1): 125–32. doi:10.3109/15513819709168352. PMID 9050066.
- MacMahon HE (July 1948). "Congenital alveolar dysplasia of the lungs". The American Journal of Pathology. 24 (4): 919–31. PMC . PMID 18874417.
- Stankiewicz P, Sen P, Bhatt SS, Storer M, Xia Z, Bejjani BA, Ou Z, Wiszniewska J, Driscoll DJ, Bolivar J, Bauer M, Zackai EH, McDonald-McGinn D, Nowaczyk MM, Murray M, Shaikh TH, Martin V, Tyreman M, Simonic I, Willatt L, Paterson J, Mehta S, Rajan D, Fitzgerald T, Gribble S, Prigmore E, Patel A, Shaffer LG, Carter NP, Cheung SW, Langston C, Shaw-Smith C (June 2009). "Genomic and genic deletions of the FOX gene cluster on 16q24.1 and inactivating mutations of FOXF1 cause alveolar capillary dysplasia and other malformations". American Journal of Human Genetics. 84 (6): 780–91. doi:10.1016/j.ajhg.2009.05.005. PMC . PMID 19500772.
- Liet JM, Joubert M, Gournay V, Godon N, Godde F, Nomballais MF, Roze JC (January 1998). "[Neonatal hypoxemia due to misaligned pulmonary vessels with alveolar capillary dysplasia]". Archives de Pédiatrie (in French). 5 (1): 27–30. doi:10.1016/s0929-693x(97)83463-x. PMID 10223108.
- Kitayama Y, Kamata S, Okuyama H, Usui N, Sawai T, Kobayashi T, Fukui Y, Okada A (January 1997). "Nitric oxide inhalation therapy for an infant with persistent pulmonary hypertension caused by misalignment of pulmonary veins with alveolar capillary dysplasia". Journal of Pediatric Surgery. 32 (1): 99–100. doi:10.1016/s0022-3468(97)90105-6. PMID 9021581.
- White, F., S. Sweet, R. M. Grady, A. Faro, P. Michelson, P. Eghtesady, U. Boston et al. (2013): In: Am J Respir Crit Care Med 187 (2013): A2251.
- MacMahon HE (July 1948). "Congenital alveolar dysplasia; a developmental anomaly involving pulmonary alveoli". Pediatrics. 2 (1): 43–57. PMID 18874463.
- Boggs S, Harris MC, Hoffman DJ, Goel R, McDonald-McGinn D, Langston C, Zackai E, Ruchelli E (January 1994). "Misalignment of pulmonary veins with alveolar capillary dysplasia: affected siblings and variable phenotypic expression". The Journal of Pediatrics. 124 (1): 125–8. doi:10.1016/S0022-3476(94)70267-5. PMID 8283361.