Two newborn babies with generalized arterial calcification of infancy, two new mutations

Severe early-onset manifestations of generalized arterial calcification of infancy (mimicking severe coarctation of the aorta) with ABCC6 gene variant - Case report and literature review

Introduction

Generalized arterial calcification of infancy (GACI) is a rare cause of infantile heart failure and systemic hypertension with a poor prognosis, characterized by extensive calcification and proliferation of the intimal layer of large and medium sized arteries.

Case report

We present the first case report of successful surgical treatment of severe aortic arch obstruction by calcified plaques mimicking severe coarctation of the aorta and the outcome (of bisphosphonate therapy) in a newborn with GACI. Furthermore, we report the identification of a variant in ATP Binding Cassette Subfamily C, Member 6 (ABCC6) gene, possibly associated with severe early-onset manifestations of GACI.

Conclusion

This case report highlights the importance of considering GACI in an infant with heart failure, systemic hypertension, and evidence of increased echogenicity of the arterial vessels. We noted the favorable outcome in improving the aortic calcification in our patient after surgical treatment and bisphosphonates therapy. Early diagnosis and treatment improve the long-term prognosis. A better understanding of this rare genetic disease could lead to new therapeutic strategies.

Mutation update: Variants of the ENPP1 gene in pathologic calcification, hypophosphatemic rickets, and cutaneous hypopigmentation with punctate keratoderma

ENPP1 encodes ENPP1, an ectonucleotidase catalyzing hydrolysis of ATP to AMP and inorganic pyrophosphate (PPi), and an endogenous plasma protein physiologically preventing ectopic calcification of connective tissues. Mutations in ENPP1 have been reported in association with a range of human genetic diseases. In this mutation update, we provide a comprehensive review of all the pathogenic variants, likely pathogenic variants, and variants of unknown significance in ENPP1 associated with three autosomal recessive disorders-generalized arterial calcification of infancy (GACI), autosomal recessive hypophosphatemic rickets type 2 (ARHR2), and pseudoxanthoma elasticum (PXE), as well as with a predominantly autosomal dominant disorder-Cole disease. The classification of all variants is determined using the latest ACMG guidelines. A total of 140 ENPP1 variants were curated consisting of 133 previously reported variants and seven novel variants, with missense variants being the most prevalent (70.0%, 98/140). While the pathogenic variants are widely distributed in the ENPP1 gene of patientsgen without apparent genotype-phenotype correlation, eight out of nine variants associated with Cole disease are confined to the somatomedin-B-like (SMB) domains critical for homo-dimerization of the ENPP1 protein.

Case Report: Coexistence of generalized arterial calcification of infancy (GACI) and maternal infections with cytomegalovirus and Toxoplasma gondii-unexpected fatal complication in a newborn

Generalized arterial calcification of infancy (GACI) is an extremely rare autosomal recessive condition characterized by the storage of calcium at the level of internal elastic membrane of arteries. The main consequences are intimal fibrous thickening and arterial occlusion. We present the case of a preterm male infant, born from an improperly dispensed pregnancy. At birth, the newborn presented generalized edema and hypotonia, and abolished heart sounds, without response to stimulation. Despite the mechanical ventilation, the infant died 2 h after birth. The death was clinically presumed to be related to the maternal infection with cytomegalovirus (CMV) and Toxoplasma gondii. The infant's mother affirmed the history of 6 previous miscarriages and a non-consanguineous marriage. At autopsy, microscopic examination showed generalized vasculitis secondary to minimal calcification of the large and medium-sized vessels of the lungs, liver, and tongue. These findings supported the diagnosis of GACI. Hydrothorax, non-infective ascites, and necrosis of the brain parenchyma were also associated. The premature infant died due to tonsillar herniation associated with decreased vessel compliance and refractory pulmonary hypertension thus leading to congestive cardiac failure. CMV was not detected on histopathological assessment nor were signs of any other infections. To the best of our knowledge, this is the first case of GACI occurring in a baby from a mother co-infected with CMV and T. gondii.

[Generalized arterial calcification in childhood: A case report]

INTRODUCTION

Arterial calcification of infancy is a rare autosomal recessive genetic disorder with extremely poor prognosis characterized by extensive calcification of internal elastic lamina and thickened of intimal tissue of large and medium sized arteries.

CASE REPORT

We present the case of a newborn necropsy with hydrops and widespread cyanosis. The internal examination revealed heart enlargement due to occlusive calcification of the arteries.

DISCUSSION

The aim of the present report is to provide a correlation of clinical and pathological features. An update of genetic diagnosis is provided.

Endogenous Calcification Inhibitors in the Prevention of Vascular Calcification: A Consensus Statement From the COST Action EuroSoftCalcNet

The physicochemical deposition of calcium-phosphate in the arterial wall is prevented by calcification inhibitors. Studies in cohorts of patients with rare genetic diseases have shed light on the consequences of loss-of-function mutations for different calcification inhibitors, and genetic targeting of these pathways in mice have generated a clearer picture on the mechanisms involved. For example, generalized arterial calcification of infancy (GACI) is caused by mutations in the enzyme ecto-nucleotide pyrophosphatase/phosphodiesterase-1 (eNPP1), preventing the hydrolysis of ATP into pyrophosphate (PP_i). The importance of PP_i for inhibiting arterial calcification has been reinforced by the protective effects of PP_i in various mouse models displaying ectopic calcifications. Besides PP_i, Matrix Gla Protein (MGP) has been shown to be another potent calcification inhibitor as Keutel patients carrying a mutation in the encoding gene or Mgp-deficient mice develop spontaneous calcification of the arterial media. Whereas PP_i and MGP represent locally produced calcification inhibitors, also systemic factors contribute to protection against arterial calcification. One such example is Fetuin-A, which is mainly produced in the liver and which forms calciprotein particles (CPPs), inhibiting growth of calcium-phosphate crystals in the blood and thereby preventing their soft tissue deposition. Other calcification inhibitors with potential importance for arterial calcification include osteoprotegerin, osteopontin, and klotho. The aim of the present review is to outline the latest insights into how different calcification inhibitors prevent arterial calcification both under physiological conditions and in the case of disturbed calcium-phosphate balance, and to provide a consensus statement on their potential therapeutic role for arterial calcification.