Alveolar capillary dysplasia
Rare congenital lung disease causing fatal respiratory failure in newborns.
Alveolar capillary dysplasia is a rare congenital lung disorder present at birth. Its hallmark is malformed lung blood vessels, which lead to severely high blood pressure in the lungs and prevent the blood from taking in oxygen and releasing carbon dioxide effectively. In newborns, symptoms usually appear within hours of birth: rapid, labored breathing and blue-tinged lips or skin. This quickly progresses to respiratory failure and death. Atypical cases have been described, where symptoms are milder at first, and the infant may survive for many months before respiratory failure sets in or a lung transplant becomes necessary.
Most cases are caused by mutations in the FOXF1 gene or its nearby regulatory region on chromosome 16. The condition follows an autosomal dominant pattern, meaning a single faulty copy of the gene or its regulator is enough to cause the disease. Exactly how these mutations disrupt lung development is not yet understood. The abnormal development includes a thickened alveolar interstitium, capillaries that are misplaced away from the alveolar surface, and an overall reduced number of capillaries. This leads to poor gas exchange and pulmonary hypertension. There is also evidence of abnormal connections between pulmonary arteries and systemic vessels, which further lowers blood oxygen levels.
Diagnosis is typically made by examining lung tissue under a microscope, either from a biopsy or during an autopsy. The key microscopic findings are pulmonary veins lying next to pulmonary arteries (instead of in their normal position with lymphatics), along with abnormal alveoli and capillary development. Genetic testing for FOXF1 is available and can confirm the diagnosis without an invasive procedure, though false negatives or uncertain results are possible because not all disease-causing mutations are known.
There are no effective treatments for severe ACD. Standard care—mechanical ventilation, pulmonary vasodilators like sildenafil or inhaled nitric oxide, and possibly ECMO—provides only temporary improvement, with symptoms returning within hours. In atypical ACD, the response to medical therapy can last for several months. For babies who can be stabilized, the only definitive treatment is bilateral lung transplantation.
ACD is very rare, with about 100 reported cases. The first case was described in 1981. Babies with ACD often have other conge
- first reported
- 1981
- reported cases
- about 100
- typical onset
- within hours to days after birth
- cause
- mutations affecting FOXF1 gene or its enhancer region
- inheritance
- autosomal dominant
- definitive treatment
- bilateral lung transplantation
Lore & Background
Alveolar capillary dysplasia is a congenital disease whose symptoms appear within hours to days after birth. Babies with ACD usually have no symptoms at the time of birth, but soon after will begin to breathe rapidly, showing increased work of breathing, and may have blue discoloration around the lips, arms, or legs, especially when feeding or crying. If an echocardiogram is performed, marked thickening of the right ventricle will be seen, resulting from highly elevated pulmonary blood pressure. ACD is generally resistant to treatment. Babies who have persistent symptoms that are poorly relieved by standard therapies for neonatal pulmonary hypertension is commonly observed in ACD. Atypical forms of ACD have been reported with only mildly rapid breathing shortly after birth, presenting with symptoms at several months of age, with symptoms improving with standard therapies for weeks to months before returning. Babies born with ACD usually have other congenital abnormalities affecting the heart, the intestines, urinary system, or genitals.
Reader's Guide
Alveolar capillary dysplasia is a rare and devastating congenital lung disease, with about 100 cases reported as of 2011. Its significance lies in its rapid and lethal course in newborns, typically leading to respiratory failure and death within hours of birth despite intensive medical support. The disease is caused by mutations affecting the FOXF1 gene or its regulatory region, inherited in an autosomal dominant pattern, though the exact mechanism linking mutations to abnormal lung development remains unknown. Diagnosis requires microscopic examination of lung tissue or genetic testing, and there are no effective treatments for severe ACD; standard therapies such as mechanical ventilation, pulmonary vasodilators, and ECMO provide only temporary improvement. For atypical cases with milder initial symptoms, response to therapy may be more sustained, and bilateral lung transplantation is the definitive treatment. ACD is likely under-recognized as a cause of neonatal death because diagnosis requires specialized testing, and death may be attributed to other congenital abnormalities that frequently accompany the disease. The first case was reported in 1981, and transmission from a carrier parent to a child was first reported in 1994.
Did You Know?
- Most cases of ACD are caused by mutations affecting the gene FOXF1 or its nearby enhancer region.
- The first case of ACD was reported in 1981.
- ACD is typically diagnosed by examination of lung tissue under a microscope, either from lung biopsy or an autopsy.
- Babies with ACD usually have other congenital abnormalities affecting the heart, intestines, urinary system, or genitals.
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