[DEFI-ALPHA cohort and POLYGEN DEFI-ALPHA clinical research hospital programme. A study about clinical, biological and genetics factors associated with the occurrence and the evolution of hepatic complications in children with alpha-1 antitrypsin deficiency]. / Cohorte DEFI-ALPHA et projet hospitalier de recherche clinique POLYGEN DEFI-ALPHA. Étude des facteurs cliniques, biologiques et génétiques associés à l'apparition et à l'évolution de complications hépatiques chez les enfants présentant un déficit en alpha-1 antitrypsine.

INTRODUCTION: The alpha-1 antitrypsin (α1-AT) deficiency, most frequently caused by homozygosity for the Z variant (SERPINA1: c.1096 G>A; Glu342Lys), can give rise to two clinical patterns: (i) respiratory impairment with emphysema (mainly in adulthood) because of a pulmonary quantitative defect in anti-elastase activity; (ii) hepatic impairment (mainly in childhood) due to the misfolding of the PiZ protein which accumulates in hepatocytes thus providing cytotoxicity. CURRENT KNOWLEDGE: To date, the clinical and genetic factors responsible for the development of major hepatic injuries (fibrosis and portal hypertension) during childhood in PiZ patients are not known. METHODS: The DEFI-ALPHA cohort, created in 2008, aims to inventory and prospectively study all α1-AT deficient children diagnosed and included after occurrence of a hepatic sign. The POLYGEN DEFI-ALPHA PHRC has recently (2013) been added to the project to identify modifiers genes by two complementary approaches: (i) the candidate genes strategy with the SERPINA1, CFTR (cystic fibrosis gene), MAN1B1 and SORL1 genes, these two latter being implied in the degradation of misfolding proteins; (ii) the whole exome sequencing (WES) strategy in families in which the PiZ proband has a PiZ brother or sister free of any hepatic sign. EXPECTED RESULTS: The clinical parameter we want to explain is the apparition of a portal hypertension in PiZ children. In the DEFI-ALPHA project, three criteria will be tested: (i) age of inclusion in the cohort, (ii) the way of inclusion (neo-natal icterus or later hepatic impairment) and (iii) treatment or not with ursodesoxycholic acid and, if so, its duration. Genetically, polymorphisms on the SERPINA1 and MAN1B1 genes have already been associated in the literature with different clinical evolutions of the A1ATD but very inconstantly. Our study thus aims to confirm or not this association. The CFTR and SORL1 genes have never been studied in the α1-AT deficiency. Finally, the whole exome sequencing strategy could allow the discovery of new unexpected modifiers genes in this disease.

Severe hereditary spherocytosis and distal renal tubular acidosis associated with the total absence of band 3.

Absence of band 3, associated with the mutation Coimbra (V488M) in the homozygous state, caused severe hereditary spherocytosis in a young child. Although prenatal testing was made available to the parents, it was declined. Because the fetus stopped moving near term, an emergency cesarean section was performed and a severely anemic, hydropic female baby was delivered. She was resuscitated and initially kept alive with respiratory assistance and hypertransfusion therapy. Cord blood smears revealed erythroblastosis, poikilocytosis, and red cells with stalk-like elongations. Band 3 and protein 4.2 were absent; spectrin, ankyrin, and glycophorin A were significantly reduced. Renal tubular acidosis was detected by the age of 3 months. Nephrocalcinosis appeared soon thereafter. After 3 years of follow-up the child is doing reasonably well on a regimen that includes regular blood transfusions and daily bicarbonate supplements. The long-term prognosis remains uncertain given the potential for hematologic and renal complications. (Blood. 2000;96:1602-1604)