1. Common molecular bases of Sudden Infant Death Syndrome and Apparent Life Threatening Events
Filonzi L1, Magnani C2, Nosetti L3, Vaghi M1, Nonnis Marzano F1
1Department of Evolutionary and Functional Biology, University of Parma. Viale delle Scienze 11, Parma, Italy
2Department of Gynecology, Obstetrics and Neonatology, University of Parma, Via Gramsci 14, Parma, Italy
3Pediatric Clinic Insubria, University of Varese, Ospedale di Circolo Fondazione Macchi, Via F. Del Ponte, Varese
INTRODUCTION
Considering previous molecular studies on the role of LL genotype of serotonin transporter (5HTT) and correlated genes (MAOA and DAT) in unexpected death in infancy (SIDS), an investigation was carried out to verify their possible involvement in apparent life threatening events (ALTE). In particular, the main objective was to verify whether or not SIDS and ALTE (including idiopathic ALTE) are a different phenotype expression of a common genetic base.
MATERIALS AND METHODS
The differential diagnosis was made in 76 generally defined ALTE with the aim of discriminating ALTE with a specific cause from idiopathic ALTE. Genotypes and allelic frequencies of DAT VNTR, MAOA VNTR and 5HTTLPR were determined in ALTE and IALTE infants and compared with data obtained from 150 healthy controls and 25 SIDS.
An agarose gel stained with ethidium bromide for the 5HTTLPR showing the three possible genotypes SS, LL and LS.
Serotonine metabolism at presynaptic and synaptic level influenced by mitochondrial monoamineoxidase A and 5HT transporter
RESULTS
No association was found between DAT polymorphisms and ALTE/IALTE groups either at genotype (P=0.25; P=0.112) or allelic (P=0.94; P=0.88) level. MAOA genotypes and allele data comparison between ALTE and control group was not significant, on the opposite data on IALTE was statistically significant for genotypes (P=0.09) and a tendency for allele (P=0.036). Analysis of 5HTT polymorphisms in IALTE remarked the role of LL genotype (P< ) and L allele (P< ) as previously demonstrated in SIDS.
DISCUSSION
Considering strict correspondence between 5HTT and MAOA genotypic and allelic data in IALTE and SIDS (but not in ALTE), we hypothesize that the two syndromes are different expressions of a common ethiopathogenesis. In particular, molecular data suggest that SIDS events could basically be IALTE episodes occurred during sleep, and therefore out of parental control. On the opposite, IALTE crisis during daytime are usually promptly managed with emergency assistance, avoiding SIDS events. Despite its functional role, results highlight the usefulness of 5HTT as a valuable tracer of SIDS risk in IALTE infants.
Comparison of 5HTTLPR genotype and allelic frequencies in different experimental groups; ALTE, IALTE, SIDS and controls
The extended publication is reported in Filonzi et al., 2012 Pediatrics 130: