Sudden infant death—focus subject of medico-legal research

A functional polymorphism in the tyrosine hydroxylase gene indicates a role of noradrenalinergic signaling in sudden infant death syndrome

OBJECTIVES

Catecholamines may contribute to the cause of sudden infant death syndrome (SIDS). TH01, a tetrameric short tandem repeat marker in the tyrosine hydroxylase gene, regulates gene expression and catecholamine production.

STUDY DESIGN

We investigated TH01 in 172 German Caucasian SIDS cases and 390 sex- and age-matched control subjects.

RESULTS

The *9.3 alleles were more frequent in patients with SIDS than in control subjects (40.12% vs 31.15%; P = .006). For homozygotes the odds ratio was 1.83 (95% confidence interval: 1.09-3.05), for carriers 1.58 (1.09-2.28). Moreover, *9.3 alleles were significantly more frequent during the winter (47.73% vs 35.38% in the warmer seasons), and the frequency of *9.3 alleles varied significantly with the age at death (weeks 7 to 12: 49.04% vs 29.63% within the first 6 weeks). Other risk factors (sleeping position, gestation, smoking) had no significant impact on the frequency of *9.3.

CONCLUSIONS

Our results indicate a relationship between SIDS and TH01 genotype, presumably caused by an impairment of breathing regulation or arousal. We propose that noradrenalinergic neuronal activity contributes to the cause of a major subset of SIDS victims. Moreover, the results further stress that SIDS is a highly heterogenic group.

Sudden Infant Death Syndrome

During the last decade, much attention has been paid to the risk factors of sudden infant death syndrome (SIDS). Many researchers have demonstrated that infant-care practices are linked to the risk of SIDS. Prone sleeping, bed sharing, maternal substance abuse, and cigarette smoking have been reported to be significant potentially modifiable risk factors for SIDS. Despite the reports that the incidence of SIDS has decreased by 38% in the United States, it remains the leading cause of death in the first year of life. Deaths resulting from child abuse or neglect inflicted or permitted by their caretakers being second only to SIDS in infant mortalities and some recommendations regarding the differentiation of SIDS and child abuse have generated speculation that some cases of infanticide were misdiagnosed as SIDS. To reach a proper conclusion as to the cause and manner of death of an infant who died suddenly and unexpectedly, investigation must be thorough and professional.

Virological analysis in the diagnosis of sudden children death: A medico-legal approach

Infections are considered to be an important cause of unexpected death in children. It has also been assumed that respiratory viruses are involved in the genesis of sudden infant death syndrome (SIDS). The Spanish National Institute of Toxicology and Forensic Sciences act as the forensic reference centre for Spain. We analyse the experience of this centre in the virological study of 64 cases of sudden children death where viral serology, virological cultures, herpesviruses polymerase chain reaction (PCR) and electron microscopy were performed. According to pathological findings, death could only be attributed to an adenovirus infection in one amygdalitis with upper airways stenosis and asphyxia. Human herpes virus 6 (HHV-6) was detected by PCR in one case with pathological findings characteristic of SIDS. Recent infection by respiratory syncytial virus (RSV), Epstein-Barr virus (EBV) and cytomegalovirus (CMV) were also detected. Meanwhile, 85.9% of the cases yielded negative viral results. Twenty-eight infants were finally categorised as SIDS. Pathological findings of infection were detected in 12 patients despite the negativity of viral analyses. Although viral infection is an uncommon cause of sudden children death, a complete microbiological investigation will help to solve the puzzle of SIDS. Definitive guidelines for microbiological analyses need to be updated whilst new pathogens are discovered or new techniques are implemented in order to clarify unsolved cases.