SAN ANTONIO – New models of autism research and treatment are increasingly looking to study specific genetic causes, including Phelan-McDermid syndrome.
Phelan-McDermid Syndrome, or PMS, is caused by deletion or mutation of the SHANK3 gene and is characterized by intellectual disability, delayed or absent speech, hypotonia, and autism spectrum disorder (ASD). Children with PMS also often have an uneven gait and other motor difficulties.
SHANK3 deletions and mutations are thought responsible for up to 2% of ASD cases; however, aberrant behavior, such as irritability, lethargy, stereotypy, hyperactivity, and inappropriate speech have not been thoroughly investigated in PMS.
Erin Li, a 4th-year medical student, presented findings at the annual meeting of the American Academy of Child and Adolescent Psychiatry from a study in children with PMS that sought to discern whether a caregiver checklist for aberrant behavior used in diagnosing ASD and intellectual disabilities could pinpoint differences in aberrant behaviors between PMS and idiopathic ASD.
The study looked at two cohorts of children, 24 with ASD caused by PMS (mean age, 7.2 years; 14 males) and 23 with idiopathic ASD (mean age, 6.4 years;15 males) using the Aberrant Behavior Checklist (ABC) developed by Michael G. Aman, Ph.D., and his colleagues. Children in both cohorts had intellectual disability, reported Ms. Li, of the Icahn School of Medicine at Mount Sinai, New York.
The ABC is a 58-item parent-reported checklist, and Ms. Li and her colleagues did not find significant differences in the severity of aberrant behavior between groups. The results suggest that, similar to idiopathic ASD, aberrant behavior in PMS can be measured using the ABC.
However, only genetic screening can detect PMS, Ms. Li noted in an interview. The best tool is the chromosomal microarray (CMA) test.
Ms. Li’s research was conducted at the Seaver Autism Center at Mount Sinai, a clinical research group headed by Dr. Alexander Kolevzon. The team also is investigating several treatments for children with PMS, including with insulinlike growth factor–1 (IGF-1), which was seen in a small pilot study (n = 9) to be associated with significant improvement in social impairment and restrictive behaviors (Mol Autism. 2014 Dec 12;5:54).
A larger study with IGF-1 is currently underway, and the group is beginning to investigate treatment of PMS with oxytocin, after results from an animal study suggested that it could improve social deficits in mice with SHANK3 deletions.
Ms. Li and her coauthors disclosed no conflicts of interest related to their findings. The director of the Seaver Autism Center, Joseph Buxbaum, Ph.D., and Mount Sinai hold a shared patent for the use of IGF-1 in PMS.