Alveolar capillary dysplasia
Encyclopedia
Alveolar capillary dysplasia (ACD, also congenital alveolar dysplasia) is a very rare congenital malformation involving abnormal development of the capillary vascular system around the alveoli of the lung
s. It is a rare cause of persistent pulmonary hypertension
in infants. It also may be a rare cause of pulmonary hypoplasia
. The outcome is neonatal death. One of the longest surviving infants lived 2 months.
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.
. This is known because ACD has been reported in multiple families. There is more than one form of ACD. In some families, a form of ACD known as alveolar capillary dysplasia with misalignment of pulmonary veins (ACD/MPV) has been linked to the gene FOXF1
on chromosome 16 q24.1-q24.2.
Sometimes ACD is diagnosed clinically. This is common when there is a family history of ACD, but rare otherwise. A clinical differential diagnosis
of ACD excludes fetal atelectasis
.
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
.
s 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. To date no such case has been reported.
lost a baby to ACD; with his first wife, Craig lost two more babies to ACD. They have founded an organization to support research into ACD.
A familial association of ACD/MPV was first reported in 1994.
Lung
The lung is the essential respiration organ in many air-breathing animals, including most tetrapods, a few fish and a few snails. In mammals and the more complex life forms, the two lungs are located near the backbone on either side of the heart...
s. It is a rare cause of persistent pulmonary hypertension
Pulmonary hypertension
In medicine, pulmonary hypertension is an increase in blood pressure in the pulmonary artery, pulmonary vein, or pulmonary capillaries, together known as the lung vasculature, leading to shortness of breath, dizziness, fainting, and other symptoms, all of which are exacerbated by exertion...
in infants. It also may be a rare cause of pulmonary hypoplasia
Pulmonary hypoplasia
Pulmonary hypoplasia is incomplete development of the lungs, resulting in an abnormally low number or size of bronchopulmonary segments or alveoli. A congenital malformation, it most often occurs secondary to other fetal abnormalities that interfere with normal development of the lungs...
. The outcome is neonatal death. One of the longest surviving infants lived 2 months.
Babies with ACD may appear normal at birth but within minutes or hours they develop respiratory distress
Respiratory distress
Respiratory distress may refer to either/both:* Labored breathing, the physical presentation of respiratory distress*Shortness of breath or dyspnea - a sensation of respiratory distress-See also:*List of terms of lung size and activity...
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
ACD is a genetic disorderGenetic disorder
A genetic disorder is an illness caused by abnormalities in genes or chromosomes, especially a condition that is present from before birth. Most genetic disorders are quite rare and affect one person in every several thousands or millions....
. This is known because ACD has been reported in multiple families. There is more than one form of ACD. In some families, a form of ACD known as alveolar capillary dysplasia with misalignment of pulmonary veins (ACD/MPV) has been linked to the gene FOXF1
FOXF1
Forkhead box protein F1 is a protein that in humans is encoded by the FOXF1 gene....
on chromosome 16 q24.1-q24.2.
Diagnosis
ACD commonly is diagnosed postmortem, by a pathologist.Sometimes ACD is diagnosed clinically. This is common when there is a family history of ACD, but rare otherwise. A clinical differential diagnosis
Differential diagnosis
A differential diagnosis is a systematic diagnostic method used to identify the presence of an entity where multiple alternatives are possible , and may also refer to any of the included candidate alternatives A differential diagnosis (sometimes abbreviated DDx, ddx, DD, D/Dx, or ΔΔ) is a...
of ACD excludes fetal atelectasis
Atelectasis
Atelectasis is defined as the collapse or closure of alveoli resulting in reduced or absent gas exchange. It may affect part or all of one lung. It is a condition where the alveoli are deflated, as distinct from pulmonary consolidation.It is a very common finding in chest x-rays and other...
.
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
Genetic counseling
Genetic counseling or traveling is the process by which patients or relatives, at risk of an inherited disorder, are advised of the consequences and nature of the disorder, the probability of developing or transmitting it, and the options open to them in management and family planning...
.
Treatment
Most babies with ACD have normal Apgar scoreApgar score
The Apgar score was devised in 1952 by the eponymous Dr. Virginia Apgar as a simple and repeatable method to quickly and summarily assess the health of newborn children immediately after birth...
s at 1 and 5 minutes, but within minutes or hours present with hypoxia
Hypoxia (medical)
Hypoxia, or hypoxiation, is a pathological condition in which the body as a whole or a region of the body is deprived of adequate oxygen supply. Variations in arterial oxygen concentrations can be part of the normal physiology, for example, during strenuous physical exercise...
and upon investigation are found to have hypoxemia
Hypoxemia
Hypoxemia is generally defined as decreased partial pressure of oxygen in blood, sometimes specifically as less than or causing hemoglobin oxygen saturation of less than 90%.-Distinction from anemia and hypoxia:...
and pulmonary hypertension. Initial treatments address the hypoxia, usually beginning with supplemental oxygen and arrangements for urgent transport to a neonatal intensive care unit
Neonatal intensive care unit
A Neonatal Intensive Care Unit —also called a Special Care Nursery, newborn intensive care unit, intensive care nursery , and special care baby unit —is an intensive care unit specializing in the care of ill or premature newborn infants.The problem of premature and congenitally ill infants is not a...
.
Therapies that have been tried to extend life include extracorporeal membrane oxygenation
Extracorporeal membrane oxygenation
In intensive care medicine, extracorporeal membrane oxygenation is an extracorporeal technique of providing both cardiac and respiratory support oxygen to patients whose heart and lungs are so severely diseased or damaged that they can no longer serve their function...
and nitric oxide
Nitric oxide
Nitric oxide, also known as nitrogen monoxide, is a diatomic molecule with chemical formula NO. It is a free radical and is an important intermediate in the chemical industry...
. 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. To date no such case has been reported.
Research
Actress NiCole Robinson and her husband Craig SnyderCraig Snyder
Craig Snyder is an American poet, writer and photographer. He is also a historian of skateboard culture.-Life and career:Born and raised in South Florida, Snyder would become a witness to the skateboard revolution which took place during the 1970s...
lost a baby to ACD; with his first wife, Craig lost two more babies to ACD. They have founded an organization to support research into ACD.
History
ACD was first described in 1948.A familial association of ACD/MPV was first reported in 1994.