The following observations are based on the 10 patients reported in the literature by Vitobello et al. and Guo et al. These patients are the only ones reported in the literature in mid 2023.
Neurodevelopmental features
Developmental delay affecting one or more areas of development is reported in almost all patients. However, its severity seems to range from mild to moderate: median age at first unassisted walk was 16.5 months and median age at first words was 14.5 months. This indicates that while some children show delayed development, others reach milestones within the normal range.
Intellectual disability
Half of the reported patients presented with mild intellectual disability. The other half exhibited normal or borderline intellectual quotient (IQ), with or without learning difficulties.
Epilepsy
Two patients were reported with epileptic features, including one with generalized tonic clonic seizures and one with epileptic aphasia. A daily treatment with carbamazepine led to a positive effect on both electroencephalography abnormalities and speech problems in the second patient.
Neuropsychiatric disorders
Half of the patients were reported with neuropsychiatric disorders, including autism spectrum disorder (atypical autism, Asperger syndrome), attention deficit/hyperactivity disorder, behavioral disorders and/or stereotypies.
Dysmorphic facial features
Nonspecific dysmorphic facial features were reported in most of the patients. However, the small number of patients reported to date makes it difficult to describe a reproducible clinical presentation, with facial features varying greatly from one patient to another.
Brain MRI
Most patients display no abnormalities on brain MRI.
Other features
Individuals may also present with hypotonia, macrocephaly, sleep disturbance and/or overweight.
ADGRL1