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Linus Biotechnology Looks to Human 'Exposome' as Biomarker for Autism Spectrum Disorders Test

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NEW YORK – Linus Biotechnology, a spinout of the Mount Sinai School of Medicine, recently announced plans to launch an assay to identify environmental exposures correlated with autism spectrum disorders in newborns.

The assay, called StrandDx-ASD, analyzes hair samples from people as young as newborns in an effort to help speed ASD diagnosis, which currently is done via behavioral observation at around 3 to 4 years of age, although some people can be diagnosed much later.

LinusBio refers to its core technology as "exposome sequencing." The idea of the exposome — the totality of environmental exposures to an individual from infancy as a complement to one's genome — was first introduced in a 2005 paper published by cancer epidemiologist Cristopher Wild while at the University of Leeds.

While the company did not offer details on the "sequencing" aspect of its technology, past research done by cofounders Manish Arora, Christine Austin, and Paul Curtin, all from Mount Sinai, has used histological and chemical analyses to examine teeth for signs of environmental exposures and of the physiological responses to them.

StrandDx-ASD is the first offering of the new company's StrandDx platform. Future assays will test hair and tooth samples for exposures to environmental factors related to higher risks of attention deficit hyperactive disorder, amyotrophic lateral sclerosis, psychosis, schizophrenia, inflammatory bowel disease, eosinophilic esophagitis, renal disease, and cancer, in addition to ASD.

"LinusBio's platform generates a timeline of past environmental exposures for individuals, as well as the biological response at hundreds of time points, all from a single sample," Arora, vice chair of the Department of Environmental Medicine and Public Health at the Icahn School of Medicine at Mount Sinai and LinusBio cofounder, said via email.

Although researchers have yet to find a causal relationship between environmental toxins and ASD, numerous studies have identified associations between ASD and exposures to factors such as heavy metals, air pollution, drug use, obesity, certain metabolites, and more across the pre-conceptual to perinatal period. The sum of these exposures is known as the exposome, first mentioned in 2009 and defined as the cumulative measure of environmental influences and associated biological responses throughout a person's lifespan.

Because of the correlations between environmental factors and ASD, academics have begun to argue for combining genetics with exposure history to assess for the risks of neuropsychiatric and other disorders.

Arora, originally a dentist, laid the seeds for the idea behind StrandDx while studying whether teeth could serve as biomarkers of lead exposure.

The layers of lead exposure he identified within teeth led him and his colleagues to broaden their search to include a wider array of chemicals and, through collaborations, foray into the ASD diagnostic field.

One of those collaborations was with Swedish researchers Sven Bölte and Kristiina Tammimies of the Karolinska Institute, who were looking for genetic patterns between discordant twins that could shed light on autism's origins.

From twins' tooth samples, Arora uncovered a pattern, in which the twin later diagnosed with ASD tended to accumulate less zinc and manganese in the third trimester of pregnancy, followed by lower levels of manganese after birth, than their unaffected twin siblings.

Based upon these and later results, the StrandDx-ASD assay was developed as a high-throughput version of Arora's past research techniques.

"The platform provides data at 500 or more time points for a large number of molecular markers," Arora said. "To do the same using blood, one would need 500 or more blood draws."

This large number of time points extends to newborns, on account of the short exposure intervals that Arora says the platform can measure.

"Our temporal resolution is as low as a few hours, so even within a month we have several hundred time points," Arora said. "The temporal resolution is adjusted to the requirements of the disease."

StrandDx-ASD recently gained FDA breakthrough device designation and LinusBio is preparing to launch a pivotal study in support of full regulatory approval.

LinusBio aims to recruit approximately 5,000 participants from birth to 21 years of age into that study. The study will assess the likelihood of ASD in children from birth to 18 months of age and evaluate the assay's ability to help in the diagnosis of ASD in those participants aged 18 months to 21 years.

"Our upcoming pivotal study will help us expand this study nationally and collect further data for regulatory approvals," Arora said. He added that the company hopes to have StrandDx-ASD on the market by 2023.

LinusBio is building toward being able to process between 500,000 to 1 million samples per year and is currently in the process of raising Series A funding.