Ambry Genetics Shares New Data on Genetic Causes for Neurodevelopmental Conditions, Further Adding to Growing Body of Evidence in Neurology

March 11, 2016

FOR IMMEDIATE RELEASE

Ambry Genetics
1 Enterprise
Aliso Viejo, CA 92656

Aliso Viejo, CA – March 11, 2016 – Ambry Genetics (Ambry), a leader in clinical genetic diagnostics and genetics software solutions, announced data identifying potential new genetic links to neurodevelopmental conditions. The findings, shared today in oral platform presentations at the American College of Medical Genetics and Genomics (ACMG) 2016 Annual Clinical Genetics Meeting in Tampa, FL, were based on genetic testing results conducted by Ambry, including diagnostic exome sequencing (DES).

“Neurodevelopmental disorders represent a challenging diagnosis because the underlying cause is not always readily understood,” said Aaron Elliott, Ph.D., Chief Operating Officer and Interim Chief Scientific Officer, Ambry Genetics. “With exome sequencing and other genetic tests, we are starting to uncover disease-causing gene mutations in neurology that may have important clinical implications.  The findings presented today in these oral presentations further add to our growing body of data that we hope will offer healthcare providers and their patients with some of the answers they are seeking.”

KIAA2022 Gene Mutations and Epileptic Encephalopathy in Women (Abstract #43)
The first oral platform presentation’s study evaluated whole genome sequencing, whole exome sequencing, and next generation sequencing panel data in females with neurodevelopmental disorders and epilepsy to identify patients with mutations in the KIAA2022 gene, found on the X chromosome.  The gene encodes a protein of unknown function, and is highly expressed in postmitotic neurons (defined as cells that no longer divide) in the fetal and adult brain.  It is thought to play a role in early brain development. Researchers looked for female patients with de novo mutations, meaning that the genetic alteration appeared for the first time in that patient and was not previously present in other family members.

Among 11 female patients identified with previously unreported de novo loss-of-function KIAA2022 mutations, 82% (n=9) had refractory generalized epilepsy with onset in infancy or early childhood.  Myoclonic seizures (brief muscle jerks) were the predominant type of seizure, occurring in 8 out of the 9 females, followed by absence seizures, or lapses in awareness (7 out of 9), and generalized tonic-clonic, or convulsive seizures (6 out of 9). 

Cognitive outcomes ranged from mild to severe intellectual disability.  All but one patient had limited speech and language skills, and autism or autistic features were found in more than half of the female patients (6 out of 11). Behavioral problems such as aggression, hyperactivity, and attention-deficit hyperactivity disorder (ADHD) were identified in 8 out of 11 females. 

“While the link between KIAA2022 mutations and neurodevelopmental conditions has been previously established in males, little is known about alterations in this gene in females,” said Katherine Helbig, MS, LCGC, a genetic counselor at Ambry Genetics and study investigator.  “We observed that, in females, the alterations in this gene cause a distinct trait, characterized by refractory myoclonic epilepsy with mild to severe intellectual disability, autistic features, and behavioral disturbances. This is different from males, who often have more severe intellectual disability and dysmorphic features, and suggests more research is needed to explain these differences.”

ASPM Gene Alterations and Marked Microcephaly (Abstract #44)
For the second oral platform presentation’s study, Ambry completed postmortem DES on a fetus with marked microcephaly to identify a potential genetic cause. Microcephaly is a congenital birth defect in which the baby’s head is smaller than expected, and is associated with incomplete brain development when severe.  The ASPM gene encodes the abnormal spindle-like microcephaly-associated protein, and alterations in this gene are associated with primary microcephaly 5, a condition characterized by decreased occipitofrontal circumference and intellectual disability.

While there was no reported family history of marked microcephaly or other findings, DES results revealed compound heterozygous ASPM alterations in the fetal sample, meaning that the sample had two pathogenic recessive mutations causing the genetic disease.

Overall, the data support that ASPM mutations were the cause of the genetic condition in the fetus.  In addition, the findings suggested that the parents have a 25% chance of having an affected pregnancy in the future, which could not have been accurately concluded based on prenatal ultrasound findings alone. 

“The findings from this case illustrate the utility of diagnostic exome sequencing in helping parents of children with existing neurodevelopmental syndromes to understand the chance of recurrence in future pregnancies,” said Christina L. Alamillo, MS, CGC, genetic counselor, Clinical Genomics at Ambry Genetics and lead study author. “This case also adds to the current literature by describing the phenotypic features observed in a fetus as a result of compound heterozygous ASPM mutations.” 

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