Co-Occurrence of Autism Spectrum Disorder and Achondroplasia

Case of twin achondroplasia and autism coexistence and literature review

Achondroplasia and autism spectrum disorder (ASD) are two genetically based disorders. The coexistence of autism with chromosomal abnormalities such as Down syndrome, monogenic syndromes such as tuberous sclerosis, Fragile X, and Rett syndrome, and microdeletion syndromes such as Phelan-McDermid syndrome helps to shed light on the genetic basis of autism spectrum disorder. The association between ASD and achondroplasia has been reported twice in the literature. In this article, we report Turkish patients who were born as identical twins from IVF pregnancy of 34 and 36-year-old parents, clinically and molecularly diagnosed with achondroplasia, and diagnosed with ASD at the age of 39 months. Our case is the first twin patient with the coexistence of achondroplasia and autism. We discuss environmental and genetic factors contributing to the development of ASD.

Expansion of the phenotypic and mutational spectrum of Carpenter syndrome

Carpenter syndrome 1 (CRPT1) is an acrocephalopolysyndactyly (ACPS) disorder characterized by craniosynostosis, polysyndactyly, obesity, and other malformations. It is caused by mutations in the gene RAB23. We are reporting on two patients from two unrelated consanguineous Egyptian families. Patient 1 presented with an atypical clinical presentation of Carpenter syndrome including overgrowth with advanced bone age, epileptogenic changes on electroencephalogram and autistic features. Patient 2 presented with typical clinical features suggestive of Carpenter syndrome. Therefore, Patient 1 was subjected to whole exome sequencing (WES) to find an explanation for his unusual features and Patient 2 was subjected to Sanger sequencing of the coding exons of theRAB23 gene to confirm the diagnosis. We identified a novel homozygous missense RAB23 variant (NM_001278668:c.T416C:p.Leu139Pro) in Patient 1 and a novel homozygous splicing variant (NM_016277.5:c.398+1G > A) in Patient 2. We suggest that the overgrowth with advanced bone age, electroencephalogram epileptogenic changes, and autistic features seen in Patient 1 are an expansion of the Carpenter phenotype and could be due to the novel missense RAB23 variant. Additionally, the novel identified RAB23 variants in Patient 1 and 2 broaden the spectrum of variants associated with Carpenter syndrome.