Neuropsychological evaluation in Lujan–Fryns syndrome: Commentary and clinical report

Genes with high penetrance for syndromic and non-syndromic autism typically function within the nucleus and regulate gene expression

BACKGROUND

Intellectual disability (ID), autism, and epilepsy share frequent yet variable comorbidities with one another. In order to better understand potential genetic divergence underlying this variable risk, we studied genes responsible for monogenic IDs, grouped according to their autism and epilepsy comorbidities.

METHODS

Utilizing 465 different forms of ID with known molecular origins, we accessed available genetic databases in conjunction with gene ontology (GO) to determine whether the genetics underlying ID diverge according to its comorbidities with autism and epilepsy and if genes highly penetrant for autism or epilepsy share distinctive features that set them apart from genes that confer comparatively variable or no apparent risk.

RESULTS

The genetics of ID with autism are relatively enriched in terms associated with nervous system-specific processes and structural morphogenesis. In contrast, we find that ID with highly comorbid epilepsy (HCE) is modestly associated with lipid metabolic processes while ID without autism or epilepsy comorbidity (ID only) is enriched at the Golgi membrane. Highly comorbid autism (HCA) genes, on the other hand, are strongly enriched within the nucleus, are typically involved in regulation of gene expression, and, along with IDs with more variable autism, share strong ties with a core protein-protein interaction (PPI) network integral to basic patterning of the CNS.

CONCLUSIONS

According to GO terminology, autism-related gene products are integral to neural development. While it is difficult to draw firm conclusions regarding IDs unassociated with autism, it is clear that the majority of HCA genes are tightly linked with general dysregulation of gene expression, suggesting that disturbances to the chronology of neural maturation and patterning may be key in conferring susceptibility to autism spectrum conditions.

Characterization of a new X-linked mental retardation syndrome with microcephaly, cortical malformation, and thin habitus

X-linked mental retardation (XLMR) affects 1-2/1,000 males and accounts for approximately 10% of all mental retardation (MR). We have ascertained a syndromic form of XLMR segregating within a five-generation family with seven affected males. Prominent characteristics include mild to severe MR, cortical malformation, microcephaly, seizures, thin build with distinct facial features including a long and thin face, epicanthic folds, almond-shaped eyes, upslanting palpebral fissures and micrognathia and behavioral problems. Carrier females have normal physical appearance and intelligence. This combination of features is unreported and distinct from Lujan-Fryns syndrome, Snyder-Robinson syndrome, and zinc finger DHHC domain-containing 9-associated MR. We propose the name of this new syndrome to be CK syndrome.