Systematic assessment of outcomes following a genetic diagnosis identified through a large-scale research study into developmental disorders.

PURPOSE: The clinical and psychosocial outcomes associated with receiving a genetic diagnosis for developmental disorders are wide-ranging but under-studied. We sought to investigate outcomes from a subset of families who received a diagnosis through the Deciphering Developmental Disorders (DDD) study. METHODS: Individuals recruited through the Peninsula Clinical Genetics Service who received a confirmed genetic diagnosis through the DDD study before August 2019 (n = 112) were included in a clinical audit. Families with no identified clinical outcomes (n = 16) were invited to participate in semistructured telephone interviews. RESULTS: Disease-specific treatment was identified for 7 probands (6%), while 48 probands (43%) were referred for further investigations or screening and 60 probands (54%) were recruited to further research. Just 5 families (4%) opted for prenatal testing in a subsequent pregnancy, reflecting the relatively advanced maternal age in our cohort, and 42 families (38%) were given disease-specific information or signposting to patient-specific resources such as support groups. Six interviews were performed (response rate = 47%) and thematic analysis identified four major themes: reaching a diagnosis, emotional impact, family implications, and practical issues. CONCLUSION: Our data demonstrate that receiving a genetic diagnosis has substantial positive medical and psychosocial outcomes for the majority of patients and their families.

De novo variants in CNOT3 cause a variable neurodevelopmental disorder.

As a result of exome-based sequencing work performed by the DDD study, de novo variants in CNOT3 have emerged as a newly recognised cause of a developmental disorder. This paper describes molecular and clinical details of 16 probands with developmental disorders and de novo CNOT3 variants. It is the first such description of the developmental phenotype associated with CNOT3 variants. Eight of these cases were discovered as part of the DDD study, while the other eight were found as a result of large-scale sequencing work performed by other groups. A highly specific phenotype was not recognised in these 16 cases. The most consistent phenotypic features seen in subjects with de novo variants in CNOT3 were hypotonia, relatively small stature, developmental delay, behavioural problems and intellectual disability. There is no easily recognisable facial phenotype, but some common dysmorphic features such as anteverted nares, thin upper lip and low set eyebrows were shared among some of the probands. Haploinsufficiency appears to be the most likely mechanism of action, with eight cases found to have protein-truncating variants. Of the other eight cases (all missense variants), three share an amino acid substitution at the same position which may therefore represent an important functional domain.