Linguistic and psychomotor development in children with chromosome 14 deletions

A complex DICER1 syndrome phenotype associated with a germline pathogenic variant affecting the RNase IIIa domain of DICER1

Background

Germline pathogenic variants in DICER1 cause DICER1 syndrome, an autosomal dominant, pleiotropic tumour predisposition syndrome with variable expressivity and reduced penetrance for specific dysplastic and neoplastic lesions. Recently, a syndrome with the acronym GLOW (Global developmental delay, Lung cysts, Overgrowth, Wilms tumour) was described in two children with mosaic missense mutations in hotspot residues of the DICER1 RNase IIIb domain.

Methods

Whole genome sequencing, exome sequencing, Sanger sequencing, digital PCR and a review of Wilms tumours with DICER1 RNase III domain mutations were performed.

Results

A de novo heterozygous c.4031C>T (p.S1344L) variant in the sequence encoding the RNase IIIa domain of DICER1 was detected. Clinical investigations revealed a phenotype that resembles the GLOW subphenotype of DICER1 syndrome.

Conclusion

The phenotypic overlap between patients with p.S1344L mutation and GLOW syndrome provide clinical support for recent discoveries that RNase IIIa-Ser1344 site mutations impede miRNA-5p biogenesis analogous to DICER1 hotspot mutations in the RNase IIIb domain. We show that an individual with a heterozygous germline p.S1344L mutation has a severe form of DICER1 syndrome (‘DICER1 syndrome plus’), with notable features of intellectual disability, macrocephaly, physical abnormalities, Wilms tumour and a well-differentiated fetal adenocarcinoma of the lung.

Guideline recommendations for diagnosis and clinical management of Ring14 syndrome-first report of an ad hoc task force

Background

Ring chromosome 14 syndrome is a rare chromosomal disorder characterized by early onset refractory epilepsy, intellectual disability, autism spectrum disorder and a number of diverse health issues.

Results

The aim of this work is to provide recommendations for the diagnosis and management of persons affected by ring chromosome 14 syndrome based on evidence from literature and experience of health professionals from different medical backgrounds who have followed for several years subjects affected by ring chromosome 14 syndrome. The literature search was performed in 2016. Original papers, meta-analyses, reviews, books and guidelines were reviewed and final recommendations were reached by consensus.

Conclusion

Conventional cytogenetics is the primary tool to identify a ring chromosome. Children with a terminal deletion of chromosome 14q ascertained by molecular karyotyping (CGH/SNP array) should be tested secondarily by conventional cytogenetics for the presence of a ring chromosome. Early diagnosis should be pursued in order to provide medical and social assistance by a multidisciplinary team. Clinical investigations, including neurophysiology for epilepsy, should be performed at the diagnosis and within the follow-up. Following the diagnosis, patients and relatives/caregivers should receive regular care for health and social issues. Epilepsy should be treated from the onset with anticonvulsive therapy. Likewise, feeding difficulties should be treated according to need. Nutritional assessment is recommended for all patients and nutritional support for malnourishment can include gastrostomy feeding in selected cases. Presence of autistic traits should be carefully evaluated. Many patients with ring chromosome 14 syndrome are nonverbal and thus maintaining their ability to communicate is always essential; every effort should be made to preserve their autonomy.

Developmental trends of communicative skills in children with chromosome 14 aberrations

Children with chromosome 14 aberrations usually show developmental delays, intellectual disability, neurological disorders and behaviour problems. The aim of the present study is to describe the developmental trajectories of the communicative skills of children with chromosome 14 aberrations, considering the possible relationships between the patterns of language development and the children's clinical characteristics (e.g., intellectual disability or autistic traits). Longitudinal data on five children (four with linear deletions and one with ring 14 syndrome) followed for 3 years are presented. Four out of five children showed profound intellectual disability, and three out of five showed autistic traits. A high individual variability was found in both vocal and gestural productions. However, only a modest increase in the children's communicative and symbolic skills was detected over time (e.g., in the quality of preverbal productions).

CONCLUSION

The increase of communicative skills in children with chromosome 14 aberration is very slow. We need to consider the children's characteristics, in terms of type of chromosome aberration, level of intellectual disability and presence/absence of autistic traits, to predict their possible linguistic outcomes and to give a more realistic expectation to their parents. What is known: • The communicative skills of children with chromosome 14 aberrations are usually impaired. • The presence of autistic traits is frequent in these children. What is new: • The increase of communicative skills in children with chromosome 14 aberrations is very slow. • The level of intellectual disability and the presence/absence of autistic traits appeared to have a role in predicting the possible linguistic outcomes in children with chromosome 14 aberrations.

Developing with ring 14 syndrome: a survey in different countries

This study aimed to assess the communicative skills of children and young adults with ring 14 syndrome and linear 14q deletions, investigating the relationships among their language development and their genetic, clinical, psychomotor and behavioural characteristics. Participants were 36 individuals with chromosome 14 aberrations whose parents completed a questionnaire, specifically developed in five languages, to assess their son's/daughter's development. Data analysis showed that chronological age does not account for the high individual variability found in the participants' skills. The comparison between participants with ring 14 syndrome and participants with 14q linear deletions showed that the former were characterised by a higher occurrence of epilepsy, abnormalities of the retina and autism. The participants with smaller amounts of deleted genetic material were those who had a higher level of language development. Because ring 14 syndrome is a rare genetic disease, the collection of data from a large group of individuals could be helpful to create expectations about the possible developmental outcomes of these children.