Table 2 Description of the 5 genes associated with a negative z score and overlapping an upregulated L1 element in all the three samples characterized by pervasive L1 upregulation

CADM2

2

Adhesion molecule that engages in homo- and heterophilic interactions with the other nectin-like family members, leading to cell aggregation. Important for synapse organization, providing regulated trans-synaptic adhesion

CSMD1

2

Weakly expressed in most tissues, except in brain (expressed at intermediate levels in brain, including cerebellum, substantia nigra, hippocampus, and fetal brain). Variants in this gene have been shown to associate with schizophrenia and bipolar disorder

DLG2

2

This gene encodes a member of the membrane-associated guanylate kinase (MAGUK) family. The encoded protein forms a heterodimer with a related family member that may interact at postsynaptic sites to form a multimeric scaffold for the clustering of receptors, ion channels, and associated signaling proteins

DLGAP1

2

The protein encoded by this gene is expressed in the brain, localizes to the postsynaptic density, and interacts with a number of ASD-associated proteins, including DLG1, DLG4, SHANK1, SHANK2 and SHANK3

GPHN

2

This gene encodes a neuronal assembly protein that anchors inhibitory neurotransmitter receptors to the postsynaptic cytoskeleton via high affinity binding to a receptor subunit domain and tubulin dimers. In non-neuronal tissues, the encoded protein is also required for molybdenum cofactor biosynthesis. Mutations in this gene may be associated with the neurological condition hyperplexia and also lead to molybdenum cofactor deficiency