Identification of a de novo case of COL5A1-related Ehlers-Danlos syndrome in an infant in the West Indies leading to improved targeted clinical care

Naturally occurring genetic diseases caused by de novo variants in domestic animals

With the advent of next-generation sequencing, an increasing number of cases of de novo variants in domestic animals have been reported in scientific literature primarily associated with clinically severe phenotypes. The emergence of new variants at each generation is a crucial aspect in understanding the pathology of early-onset diseases in animals and can provide valuable insights into similar diseases in humans. With the aim of collecting deleterious de novo variants in domestic animals, we searched the scientific literature and compiled reports on 42 de novo variants in 31 genes in domestic animals. No clear disease-associated phenotype has been established in humans for three of these genes (NUMB, ANKRD28 and KCNG1). For the remaining 28 genes, a strong similarity between animal and human phenotypes was recognized from available information in OMIM and OMIA, revealing the importance of comparative studies and supporting the use of domestic animals as natural models for human diseases, in line with the One Health approach.

A novel unbalanced translocation between chromosomes 5p and 18q leading to dysmorphology and global developmental delay

Background

Individuals with various sized terminal duplications of chromosome 5p or terminal deletions of chromosome 18q have been described. These aberrations may cause congenital malformations and intellectual disability of varying severity.

Methods

Via an international collaborative effort, we obtained a cytogenetic diagnosis for a 5‐year‐old boy of Afro‐Caribbean ancestry who has global developmental delay, dysmorphology, hypotonia, feeding difficulties, bilateral club feet, and intellectual disability.

Results

Conventional G‐banded karyotyping showed additional chromatin of unknown origin on the long arm of chromosome 18. SNP microarray confirmed the loss of ~6.4 Mb from chromosome 18q: arr[hg19] 18q22.3‐q23(71,518,518‐77,943,115)x1. The source of the additional chromatin was determined from the microarray to be ~32 Mb from the short arm of chromosome 5 (arr[hg19] 5p13.3‐p15.33(51,045‐32,062,984)x3). The unbalanced translocation was verified by fluorescent in situ hybridization (FISH). Both parents are healthy and have normal karyotypes suggesting that this abnormality arose de novo in the proband, although gonadal mosaicism in a parent cannot be excluded.

Conclusion

The combination of clinical features in this individual is most likely due to the partial deletion of 18q and partial duplication of 5p, which to our knowledge has not been previously described.

Experiences with offering pro bono medical genetics services in the West Indies: Benefits to patients, physicians, and the community

We describe our experiences with organizing pro bono medical genetics and neurology outreach programs on several different resource-limited islands in the West Indies. Due to geographic isolation, small population sizes, and socioeconomic disparities, most Caribbean islands lack medical services for managing, diagnosing, and counseling individuals with genetic disorders. From 2015 to 2019, we organized 2-3 clinics per year on various islands in the Caribbean. We also organized a week-long clinic to provide evaluations for children suspected of having autism spectrum disorder. Consultations for over 100 different individuals with suspected genetic disorders were performed in clinics or during home visits following referral by locally registered physicians. When possible, follow-up visits were attempted. When available and appropriate, clinical samples were shipped to collaborating laboratories for molecular analysis. Laboratory tests included karyotyping, cytogenomic microarray analysis, exome sequencing, triplet repeat expansion testing, blood amino acid level determination, biochemical assaying, and metabolomic profiling. We believe that significant contributions to healthcare by genetics professionals can be made even if availability is limited. Visiting geneticists may help by providing continuing medical education seminars. Clinical teaching rounds help to inform local physicians regarding the management of genetic disorders with the aim of generating awareness of genetic conditions. Even when only periodically available, a visiting geneticist may benefit affected individuals, their families, their local physicians, and the community at large.