OBSOLETE: Uniparental disomy of chromosome 6

Uniparental disomy of chromosome 6 (UPD6) is a rare chromosomal anomaly in which both copies of chromosome 6 are inherited from a single parent rather than one from each parent. This Orphanet entry (263024) is classified as OBSOLETE, meaning it has been retired or reorganized within current classification systems. Historically, UPD6 has been associated with distinct clinical consequences depending on whether both copies are inherited from the mother (maternal UPD6) or the father (paternal UPD6). Paternal uniparental disomy of chromosome 6 is notably associated with transient neonatal diabetes mellitus (TNDM), a condition characterized by intrauterine growth restriction, hyperglycemia presenting in the neonatal period, and dehydration. This occurs due to overexpression of imprinted genes in the 6q24 region. Maternal UPD6 has been less consistently associated with a specific phenotype but may be linked to intrauterine growth restriction in some cases. Because this entry is obsolete, patients and clinicians should refer to the more specific current Orphanet entries for conditions resulting from UPD6, such as transient neonatal diabetes mellitus (Orphanet: 99886). Management of associated conditions like TNDM typically involves insulin therapy during the neonatal period, with diabetes usually resolving within months, though it may recur later in life. Genetic counseling is recommended for affected families.

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