OBSOLETE: Uniparental disomy of chromosome 1

Uniparental disomy of chromosome 1 (UPD1) is a rare genetic condition in which a person inherits both copies of chromosome 1 from one parent instead of receiving one copy from each parent. This entry is labeled as 'OBSOLETE' in the Orphanet classification, meaning it has been retired or reclassified, often because the condition is now understood as part of a broader group of uniparental disomy disorders or because the clinical features overlap with other recognized conditions. In a normal situation, you get one chromosome 1 from your mother and one from your father. In UPD1, both copies come from either the mother (maternal UPD1) or the father (paternal UPD1). This matters because some genes on chromosome 1 may be 'imprinted,' meaning they work differently depending on which parent they came from. When both copies come from one parent, imprinted genes may not function correctly, and there is also a risk that recessive disease genes carried by that parent could be unmasked, leading to autosomal recessive conditions. The symptoms of UPD1 can vary widely depending on whether the disomy is maternal or paternal, which specific regions of chromosome 1 are involved, and whether any recessive disease genes are present. Reported features in some cases have included growth problems, developmental delays, and other variable findings. Because this is an obsolete classification, patients identified with UPD1 are now typically evaluated on a case-by-case basis, with treatment directed at whatever specific symptoms or conditions arise. There is no single standard treatment for UPD1 itself; management focuses on addressing individual health concerns.

Bring these to your next appointment

• Q1.Is the uniparental disomy in my child maternal or paternal, and does that make a difference?,Are there any autosomal recessive conditions that have been unmasked by this UPD?,Are there known imprinted genes on chromosome 1 that could be affected?,What developmental screenings and monitoring should we schedule?,Should other family members be tested?,What early intervention services would you recommend?,How often should we follow up with a geneticist?

Common questions about OBSOLETE: Uniparental disomy of chromosome 1