Phenotypic variation in two patients with a ring chromosome 22

Abstract

Two severely mentally retarded patients with a ring chromosome 22 presented with disparate phenotypes: one patient manifested only minimal dysmorphic features, whereas the other had a distinctive pattern of anomalies consisting of an abnormal skull configuration with mild maxillary hypoplasia, a large nose, thick full lips, a protruding tongue, lymphedema, hypotonia and an unsteady gait. The findings in these and previously reported patients indicate that a ring chromosome 22 is usually associated with moderate to severe mental retardation, with a range of dysplastic features from mild and nonspecific to more marked and distinctive.

Clinical, cytogenetic, and molecular characterization of six patients with ring chromosomes 22, including one with concomitant 22q11.2 deletion

“…Ritter et al [] described a patient presenting mosaicism with hypomelanosis of Ito similar to our patient who presented a mottled pattern of hypochromic maculae over the dorsum, abdomen, and lower limbs and patchy depigmentation of the upper limbs. Not surprisingly, patients with a ring chromosome 22 have some features in common with carriers of a linear 22q13 deletion, including global intellectual disability, severe speech delay, autism spectrum disorders, behavioral disorders, hypotonia, abnormal ears, epicanthal folds, and hypoplastic toenails [Hunter et al, ; Funderburk et al, ; Nesslinger et al, ; Prasad et al, ; De Mas et al, ; Sarasua et al, ]. In fact, Patients 2, 4, 5, and 6 have a deletion in 22q13 and present speech delay.…”

The use of sequential silver and quinacrine staining to determine the parental origin and breakpoints of a ring‐22 human chromosome

“…in the interim (Hunter et al 1977), it is now certain that a "ring-22 syndrome" exists (de Grouchy & Turleau 1977). A recent report by Funderburk et al (1979) demonstrates, however, that there is considerable variability in its expression. The syndrome is presumably due to loss of material from the long arm (9) of 22, since the short arm (p) of 22 is known to be dispensable without ill effects (e.g., in Robertsonian translocations).…”