Ring chromosomes

References
Somatic mosaicism of chromosome 7 in a highly proliferating melanocytic congenital naevus in a ring chromosome 7 patient. Mehraein Y, Ehlhardt S, Wagner A, Göttert E, Tilgen W, Zang KD, Dill-Müller D. Am J Med Genet A. 2004 Dec 1;131(2):179-85. PMID: #15523614#

Synopsis
hypotonia
dysmorphia (facial dysmorphism)
mild-to-moderate mental retardation
Variants
mosaic ring chromosome 17 (#12774038#)
References
Dupont C, Pipiras E, Chantot-Bastaraud S, Verloes A, Baumann C, Wolf JP, Benzacken B. CGH and direct diagnosis of mosaic structural chromosomal abnormalities: description of a mosaic ring chromosome 17 and review of the literature. Eur J Hum Genet. 2003 Jun;11(6):452-6. PMID: (...)

This catastrophic epileptic syndrome was first described by Atkins et al. in 1972.
The clinical presentation is characterized by mental retardation, behavioral disorders, and epilepsy.
The absence of (or only minimal) dysmorphic features usually delay accurate diagnosis.
The seizures typically start around age 5 years, are of several types, and are refractory to therapy. However, nocturnal frontal lobe seizures are frequently encountered, as well as nonconvulsive status epilepticus and (...)

ring chromosome 15 syndrome, ring chromosome 15 with15q26.1-qter deletion

r(4)(p16—>q22.3) , deleted ring chromosome 4