Atypical hemolytic uremic syndrome induced by SARS-CoV2 infection in infants with EXOSC3 mutation.

BACKGROUND: Atypical hemolytic uremic syndrome (aHUS) is a rare disease characterized by systemic thrombotic microangiopathy mainly in the kidneys and mostly due to genetic disorders leading to uncontrolled activation of the complement system. Severe complications of SARS-CoV2 infection are linked to microvascular injury and complement activation is suspected to play a role in the pathogenesis of endothelial cell damage in severe COVID-19. METHODS: We present the first two cases of aHUS triggered by SARS-CoV-2 infection in two unrelated infants with the same mutation in the RNA exosome gene EXOSC3. This mutation is known to cause pontocerebellar hypoplasia type 1b, an autosomal-recessive neurodegenerative disease. So far, no kidney involvement in affected persons was reported. RESULTS: As eculizumab treatment was unsuccessful and complement-mediated disorders were ruled out, we suppose that the atypical HUS in our two patients is not due to complement-mediated thrombotic microangiopathy but rather due to a dysfunction of the RNA exosome. CONCLUSIONS: The RNA exosome is crucial for the precise processing and degradation of nuclear and cytoplasmatic RNA. We suspect that the SARS-CoV-2 infection led to changes in RNA that could not be offset by the defective RNA exosome in our two patients. The accumulation/wrong processing of the viral RNA must have led to the endothelial cell damage resulting in aHUS. This would be a new - "RNA-induced" - mechanism of aHUS.

[A Newborn Suffering from Arhinia: Neonatologic Challenges During Primary Care of the Newborn With Bosma Arhinia Microphthalmia Syndrome (BAMS)]. / Neugeborenes mit Nasenagenesie: Neonatologische Herausforderungen bei der Versorgung eines Neugeborenen mit Bosma-Arhinie-Mikrophthalmie-Syndrom (BAMS).

The rare clinical picture of nasal agenesis is to be presented on the basis of a female newborn. Intrauterine growth restriction with polyhydramnios and midface hypoplasia were noted during pregnancy. Primary cesarean section at 38 + 4 weeks' gestation was done. Airway management was achieved by splinting through a Mayo tube which was subsequently replaced by a pharyngeal endotracheal tube without signs of respiratory failure. In addition to a complete nasal agenesis, hypertelorism, a Gothic palate, bilateral microphthalmus, and iris coloboma were found. Ultrasound scans of cerebral structures were normal. An orogastric tube was placed, and drinking training and a special pacifier improved coordination and drinking performance. We suspected a case of Bosma arhinia microphthalmia syndrome (BAMS). The structural maintenance of chromosomes flexible hinge domain (SMCHD) containing 1 gene plays a key role in the embryogenesis of the human nose and is known for mutations in BAMS. A heterozygous de novo mutation in the SMCHD1 gene (c.1043A > G; pHis348Arg) was confirmed by molecular genetic analysis. Initial stabilization after birth is often a challenge in patients with nasal agenesis. They are often intubated immediately postpartum and electively tracheotomized. In the absence of respiratory problems and appropriate growth, however, there is no urgent indication for early plastic surgical treatment, given the inherent risks of sepsis and growth disorders in the midface.