Maternal and paternal uniparental disomy of chromosome 13 have been associated with normal phenotypes. We report on a new case of paternal isodisomy 13 in a phenotypically normal girl. Prenatal diagnosis had shown a 46,XX,-13,der(13;13) karyotype in chorionic villi and a 45,XX,der(13;13) karyotype in amniocytes and fetal blood. Molecular studies demonstrated that the de novo der(13;13) was an isochromosome 13 of paternal origin. This observation supports the lack of imprinting effects on chromosome 13 and trisomy rescue as a mechanism leading to uniparental disomy in cases involving isochromosomes.
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Int J Legal Med
March 2025
Diagnósticos da América S. A., DASA, São Paulo, Brazil.
Uniparental disomy (UPD) is the abnormal situation in which both members of a chromosome pair exclusively comprise material of one of the parents. The incidence of UPD is estimated in 1:2000 live births. This rare condition is relevant for medical genetics due to imprinting disorders or recessive diseases; however, it may also impact for parentage testing, leading to apparent false parentage.
View Article and Find Full Text PDFMol Cytogenet
February 2025
Departments of Pathology and Laboratory Medicine, UT-Health San Antonio, 7703 Floyd Curl Drive, San Antonio, TX, 78229, USA.
Background: Gestational trophoblastic neoplasms consist of complete and partial hydatidiform moles, both of which are considered aberrant conceptuses. Both conditions, complete hydatidiform mole (CHM) and partial hydatidiform mole (PHM), differ in histological characteristics, genetic origin and content and clinical features. CHM have a diploid karyotype, mostly 46,XX but lack maternal genetic contribution with all chromosomes of paternal origin.
View Article and Find Full Text PDFMol Genet Genomic Med
January 2025
Department of Ophthalmology, Seoul National University College of Medicine, Seoul National University Hospital, Seoul, Korea.
Background: Leber congenital amaurosis (LCA), the most severe form of inherited retinal dystrophy, is a rare, heterogeneous, genetic eye disease associated with severe congenital visual impairment. RPE65, one of the causative genes for LCA, encodes retinoid isomerohydrolase, an enzyme that plays a critical role in regenerating visual pigment in photoreceptor cells.
Methods: Exome sequencing (ES) was performed on a patient with suspected LCA.
Taiwan J Obstet Gynecol
January 2025
Medical Genetics and Prenatal Diagnosis Department, Shiyan Maternal and Child Health Hospital, Shiyan, Hubei, PR China. Electronic address:
Front Endocrinol (Lausanne)
December 2024
Rare Disease Research Group, Molecular (Epi) Genetics Laboratory, Bioaraba Health Research Institute, Araba University Hospital, Vitoria-Gasteiz, Spain.
Objective: To identify the genetic cause underlying the methylation defect in a patient with clinical suspicion of PHP1B/iPPSD3.
Design: Imprinting is an epigenetic mechanism that allows the regulation of gene expression. The locus is one of the loci within the genome that is imprinted.
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