Partial mosaic trisomy 5: A new case report with ocular involvement

Healthy Genetically Normal Live-Birth After Mosaic Chromosome 5 Embryo Transfer: A Case Report

Embryonic mosaicism is defined as two or more distinct cell lines within an embryo, which is originally developed from a zygote. Although the potential of mosaic embryos still remain unclear, recent reports have proved that mosaic embryo transfer can achieve healthy live-births. Up to now, there is no report of a live-birth having mosaic trisomy of full chromosome 5 following in-vitro fertilization (IVF). Our case is the first case proving that the transfer of medium-mosaicism embryo can result in a healthy live-birth. The couple are both carriers of balanced reciprocal translocations (46,XX,t(2;8)(p23;q24.3) and 46,XY,t(12;16)(q13.2;q23)). They had three IVF cycles combined with PGT-SR (Preimplantation Genetic Testing for Structural Rearrangement). A total of 18 blastocysts were biopsied and no euploid embryo was found. After the conselling, the patients chose to transfer a 40% mosaic trisomy chromosome 5 embryo. The follow-up pregnancy including prenatal diagnosis, amniocentesis and peripheral blood chromosome analysis of the newborn revealed no trisomy chromosome 5.

Systemic and ocular manifestations of a patient with mosaic ARID1A-associated Coffin-Siris syndrome and review of select mosaic conditions with ophthalmic manifestations

Mosaic genetic mutations may be somatic, germline, or "gonosomal" and have the potential to cause genetic syndromes, disorders, or malformations. Mutations can occur at any point in embryonic development and the timing determines the extent of distribution of the mutation throughout the body and different tissue types. The eye and visual pathway offer a unique opportunity to study somatic and gonosomal mosaic mutations as the eye consists of tissues derived from all three germ layers allowing disease pathology to be assessed with noninvasive imaging. In this review, we describe systemic and ocular manifestations in a child with mosaic Coffin-Siris syndrome. The patient presented with a significant medical history of accommodative esotropia and hyperopia, macrocephaly, polydactyly, global developmental delay, hypotonia, ureteropelvic junction (UPJ) obstruction, and brain MRI abnormalities. The ophthalmic findings in this patient were nonspecific, however, they are consistent with ocular manifestations reported in other patients with Coffin-Siris syndrome. We also review ophthalmic findings of select mosaic chromosomal and single-gene disorders. Ophthalmic assessment alongside clinical genetic testing may play an important role in diagnosis of genetic syndromes as well as understanding disease pathology, particularly when mosaicism plays a role.

Ring autosomes: some unexpected findings

Ring chromosomes are rare entities, usually associated with phenotypic abnormalities in correlation with the loss of genetic material. There are various breakpoints and sometimes there is a dynamic mosaicism that is reflected in clinical features. Most of the ring chromosomes are de novo occurrences. Our study reflects the experience of three Romanian cytogenetic laboratories in the field of ring chromosomes. We present six cases with ring chromosomes involving chromosomes 5, 13, 18, and 21. All ring chromosomes were identified after birth in children with plurimalformative syndromes. The ring chromosome was present in mosaic form in three cases, and this feature reflects the ring's instability. In case of ring chromosome 5, we report a possible association with oculo-auriculo-vertebral spectrum.