STRENGTHS AND LIMITATIONS OF THIS STUDY
Uniparental disomy can cause both imprinting disorders and recessive diseases in the same patient.
We report here the first case of Tay-Sachs disease transmitted via heterodisomy from a homozygous mother.
Trio analysis is crucial to detect uniparental disomy and guide accurate genetic counselling.
IntroductionFirst described in 1980, the concept of UPD refers to the presence, in an individual, of either part or whole chromosomal pair inherited from a single parent.1 There are three subtypes of UPD: (1) isodisomy (isoUPD) in which the same identical chromosome is inherited twice from the same parent (whole chromosomal homology); (2) heterodisomy (heteroUPD) defined by the presence of two different homologous chromosomal pairs from the same parent; (3) mixed iso-/heterodisomy (mixedUPD) when both isodisomic and heterodisomic segments occur in one chromosome, resulting from meiotic recombination. UPD is estimated to occur in approximately 1 in 2000 births and is…
