2023 ACMG Annual Clinical Genetics Meeting Digital Edition: Poster Gallery-Prenatal diagnosis of 7q, Xq/Yq deletion mosaicism in an alobar holoprosencephaly fetus: A case report and review of the literature

Prenatal diagnosis of 7q, Xq/Yq deletion mosaicism in an alobar holoprosencephaly fetus: A case report and review of the literature

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This case report discusses the prenatal diagnosis of 7q and Xq/Yq deletion mosaicisim in a fetus with alobar holoprosencephaly (HPE). HPE is a congenital malformation of the brain and face caused by incomplete cleavage of the prosencephalon. Alobar HPE is the most severe form and is associated with high perinatal mortality. Most cases of HPE are sporadic, but some have identifiable genetic causes. In this case, a 12-week ultrasound revealed isolated alobar HPE in an 18-year-old pregnant woman. Chorionic villus sampling detected an abnormal mosaic karyotype with 7q deletion and Xq/Yq loss. Further analysis confirmed the presence of a male fetus with X/XY mosaicism and pathogenic deletion on chromosome 7. Notably, the deletion includes the SHH gene, a major gene implicated in HPE. The parents' karyotypes and expanded carrier screening were normal.<br /><br />The genetics of HPE are complex and involve various genetic causes. Mosaicism may play a role in the clinical manifestation, but its extent is unclear. The 7q deletion has been frequently linked to HPE, but its genotype-phenotype relationship has not been fully defined. This case emphasizes the importance of early prenatal diagnosis, appropriate counseling, and diagnostic testing for HPE. <br /><br />In conclusion, this case report presents a prenatal diagnosis of alobar HPE associated with mosaic terminal deletion of 7q. The significance of mosaicism in contributing to the clinical features of HPE remains uncertain. Timely and accurate genetic evaluation is crucial in cases of HPE to guide counseling and management decisions.

Asset Subtitle

Presenting Author - Jee Hey Song, MD; Co-Author - Zenobia Gonsalves, MD; Co-Author - Anna Karlsen, MS, CGC; Co-Author - Desiree Fiorentino, MD, MBA, FACMG, FACOG; Co-Author - Pe'er Dar, MD; Co-Author - Sara S. Rabin-Havt, MD; Co-Author - Susan Klugman, MD;

Meta Tag

array CGH

Brain/Nervous System

Chromosomal Abnormalities

Congenital Anomaly

Counseling

Genetic Testing

Genotype-Phenotype Correlations

Microarray

Prenatal Diagnosis

Ultrasound

Co-Author Zenobia Gonsalves, MD

Co-Author Anna Karlsen, MS, CGC

Co-Author Desiree Fiorentino, MD, MBA, FACMG, FACOG

Co-Author Pe'er Dar, MD

Co-Author Sara S. Rabin-Havt, MD

Co-Author Susan Klugman, MD

Presenting Author Jee Hey Song, MD

Keywords

prenatal diagnosis

7q deletion

Xq/Yq deletion

mosaicism

alobar holoprosencephaly

HPE

congenital malformation

prosencephalon

perinatal mortality

genetic causes