Familial pulmonary capillary hemangiomatosis early in life

Pulmonary capillary hemangiomatosis: a case series and review of literature

Pulmonary capillary hemangiomatosis (PCH) is a rare cause of pulmonary hypertension (PH) of unknown etiology resulting from pulmonary capillary proliferation. Clinically, PCH is seen in young adults with equal sex predilection and rarely reported familial predisposition. PCH's main clinical presentations are progressive dyspnea, fatigue, hemoptysis, palpitations, and later irreversible pulmonary hypertension and right-sided heart failure. Hereby, we report three PCH cases, each case presented with a peculiar presentation with a comprehensive literature review highlighting etiology, clinical presentations, diagnostic modalities and pathology in establishing a diagnosis, current treatment options, and prognosis of PCH. In conclusion, defining PCH as the underlying cause of PH is of utmost importance as most medications used for PH are ineffective in PCH. Vasodilators should be avoided due to the increased risk of pulmonary oedema. Pathological examination of the lung is still considered the most definitive diagnostic tool, yet it is associated with complications risk. High-Resolution Computed Tomography (HRCT) chest is currently considered the cornerstone non-invasive modality for the diagnosis of PH. So far, no definitive treatment of PCH excluding lung transplantation with preliminary promising results with angiogenesis Inhibitors. PCH carries a very poor prognosis with a median survival of 3 years from the time of diagnosis.

A 16q deletion involving FOXF1 enhancer is associated to pulmonary capillary hemangiomatosis

BACKGROUND

Pulmonary capillary hemangiomatosis (PCH) is an uncommon pulmonary disorder, with variable clinical features depending on which lung structure is affected, and it is usually linked to pulmonary arterial hypertension. Congenital PCH has been very rarely described and, so far, the only causative gene identified is EIF2AK4, which encodes for a translation initiation factor. However, not all PCH cases might carry a mutation in this gene.

CASE PRESENTATION

We report the clinical and cytogenetic characterization of a patient (male, newborn, first child of healthy non-consanguineous parents) died after three days of life with severe neonatal pulmonary hypertension, due to diffuse capillary hemangiomatosis diagnosed post mortem. Conventional karyotyping, Microarray-Based Comparative Genomic Hydridization (CGHa) and quantitative PCR were performed. CGHa revealed a heterozygous chromosome 16q23.3q24.1 interstitial deletion, spanning about 2.6 Mb and involving a FOXF1 gene enhancer. Quantitative PCR showed that the proband's deletion was de novo. Microsatellite analysis demonstrate that the deletion occurred in the maternal chromosome 16.

CONCLUSION

FOXF1 loss of function mutation have been so far identified in alveolar capillary dysplasia with misalignment of pulmonary veins (ACD/MPV), a lung disease different from PCH. Our data suggest the hypothesis that disruption of the FOXF1 gene enhancer could be a genetic determinant of PCH. Moreover, our findings support the idea that FOXF1 is a paternally imprinted gene.

Pulmonary capillary hemangiomatosis: a focus on the EIF2AK4 mutation in onset and pathogenesis

Pulmonary capillary hemangiomatosis (PCH) is a pulmonary vascular disease that mainly affects small capillaries in the lung, and is often misdiagnosed as pulmonary arterial hypertension or pulmonary veno-occlusive disease due to similarities in their clinical presentations, prognosis, and management. In patients who are symptomatic, there is a high mortality rate with median survival of 3 years after diagnosis. Both idiopathic and familial PCH cases are being reported, indicating there is genetic component in disease etiology. Mutations in the eukaryotic translation initiation factor 2α kinase 4 (EIF2AK4) gene were identified in familial and idiopathic PCH cases, suggesting EIF2AK4 is a genetic risk factor for PCH. EIF2AK4 mutations were identified in 100% (6/6) of autosomal recessively inherited familial PCH and 20% (2/10) of sporadic PCH cases. EIF2AK4 is a member of serine/threonine kinases. It downregulates protein synthesis in response to a variety of cellular stress such as hypoxia, viral infection, and amino acid deprivation. Bone morphogenetic protein receptor 2 (BMPR2) is a major genetic risk factor in pulmonary arterial hypertension and EIF2AK4 potentially connects with BMPR2 to cause PCH. L-Arginine is substrate of nitric oxide synthase, and L-arginine is depleted during the production of nitric oxide, which may activate EIF2AK4 to inhibit protein synthesis and negatively regulate vasculogenesis. Mammalian target of rapamycin and EIF2α kinase are two major pathways for translational regulation. Mutant EIF2AK4 could promote proliferation of small pulmonary arteries by crosstalk with mammalian targets of the rapamycin signaling pathway. EIF2AK4 may regulate angiogenesis by modulating the immune system in PCH pathogenesis. The mechanisms of abnormal capillary angiogenesis are suggested to be similar to that of tumor vascularization. Specific therapies were developed according to pathogenesis and are proved to be effective in reported cases. Targeting the EIF2AK4 pathway may provide a novel therapy for PCH.

EIF2AK4 mutations in pulmonary capillary hemangiomatosis

BACKGROUND

Pulmonary capillary hemangiomatosis (PCH) is a rare disease of capillary proliferation of unknown cause and with a high mortality. Families with multiple affected individuals with PCH suggest a heritable cause although the genetic etiology remains unknown.

METHODS

We used exome sequencing to identify a candidate gene for PCH in a family with two affected brothers. We then screened 11 unrelated patients with familial (n = 1) or sporadic (n = 10) PCH for mutations.

RESULTS

Using exome sequencing, we identified compound mutations in eukaryotic translation initiation factor 2 α kinase 4 (EIF2AK4) (formerly known as GCN2) in both affected brothers. Both parents and an unaffected sister were heterozygous carriers. In addition, we identified two EIF2AK4 mutations in each of two of 10 unrelated individuals with sporadic PCH. EIF2AK4 belongs to a family of kinases that regulate angiogenesis in response to cellular stress.

CONCLUSIONS

Mutations in EIF2AK4 are likely to cause autosomal-recessive PCH in familial and some nonfamilial cases.