Ring chromosome

A ring chromosome is when two ends of a chromosome come together and look like a ring. This can happen to any chromosome. It was first discovered in 1926 by American biologist Lilian Vaughan Morgan. There are many different symptoms someone may have if they have a ring chromosome. The most common symptom is a delay in growth. Most of the time, ring chromosomes happen randomly. About 1 in 50,000 people have a ring chromosome.

 Formation 
Most of the time, a ring chromosome will happen if the two ends of one chromosome are missing. This allows the ends to combine together to form a ring. Sometimes, the ends of the chromosomes won't be missing, but this is very rare. When this happens, the phenotype (appearance and body) of someone is usually normal. They usually do not know they have a ring chromosome.

Ring chromosomes can be very complicated. Sometimes, small parts of the chromosome may be missing (microdeletion) or there may be a copy of it (microduplication).  Sometimes, someone may have three chromosomes (trisomy) instead of two with the extra chromosome being a ring chromosome.

Any chromosome can be a ring chromosome.

 Ring chromosome syndromes 
A ring chromosome syndrome is any genetic disorder that is caused by a ring chromosome. About 1 in 50,000 people have a ring chromosome syndrome. The symptoms vary based on which chromosome is the ring chromosome. Most of the time, the symptoms vary widely, even in the same ring chromosome syndrome. However, most syndromes with a ring chromosome affect the way someone's body grows.

 List of ring chromosome syndromes 
+ChromosomeCommon symptomsPrevalenceRing chromosome 1Microcephaly (small head), intellectual disability, developmental delay<1 in 1,000,000Ring chromosome 2Developmental delay, skeleton issues, genital issues, deformities<1 in 1,000,000Ring chromosome 3Developmental delay, intellectual disability, deformities<1 in 1,000,000Ring chromosome 4Low birth weight, deformities, heart defects<1 in 1,000,000Ring chromosome 5Deformities, heart issues, skeletal issues, intellectual disabilityUnknownRing chromosome 6Deformities, small eyes, intellectual disability<1 in 1,000,000Ring chromosome 7Intellectual disability, genital issues, skin issues, deformities<1 in 1,000,000Ring chromosome 8Minor deformities, intellectual disability<1 in 1,000,000Ring chromosome 9Developmental delay, intellectual disability, deformities<1 in 1,000,000Ring chromosome 10Developmental delay, intellectual disability, microcephaly<1 in 1,000,000Ring chromosome 11Developmental delay, intellectual disability, microcephaly<1 in 1,000,000Ring chromosome 12Heart issues, intellectual disability, developmental delay, microcephaly<1 in 1,000,000Ring chromosome 13Deformities, intellectual disability, developmental delay, genital issuesRing chromosome 14Epilepsy, intellectual disability<1 in 1,000,000Ring chromosome 15Intellectual disability, developmental delay, heart issues, spots of different colored skin<1 in 1,000,000Ring chromosome 16Developmental delay, intellectual disability, deformities<1 in 1,000,000Ring chromosome 17Intellectual disability, deformities, seizures<1 in 1,000,000Ring chromosome 18Developmental delay, intellectual disability, deformities<1 in 1,000,000Ring chromosome 19Physical issues, learning disability, intellectual disability<1 in 1,000,000Ring chromosome 20Epilepsy<1 in 1,000,000Ring chromosome 21Physical issues, intellectual disability, epilepsyUnknownRing chromosome XSymptoms of Turner synrdomeRing chromosome YShort height, infertility, ambiguous genitalia, bipolar disorderUnknown

 References 

Category:Chromosomes