Ring chromosome 5 with dental anomalies.

Although ring chromosomes are observed in ahnost all autosomal groups in man, they are rare. We describe a male patient exldbiting cd du chat syndrome in which cytogenetic studies demonstrate the presonse of a ring chromosome 5. Deletion o£ the ring chromosome 5 is found between the p15 and q35 bands. Dental, medical and cytogenetic findings are compared to other ring chromosome 5 cases descMbed in literature. Introduetion Cri du chat syndrome, first described in 1963,~ is characterized by a shrill high cry similar to that of a young cat. The cry is attributed to a hypotonic, dysmorphic larynx noted in some patients. ~ The cry may not be pathognomonic of the syndrome since it is absent in some patients and is reported in other chromosomal abnormalities? The following traits may be found during infancy: ~,~ microcephaly, round facies, apparent ocular hypertelorism, downward slant of palpebral fissures, epicanthal folds, low-set posteriorly angt}.lated ears, preauricular tags, micrognathia/retrognathia, prominent nasal bridge, muscular hypotonia, congenital defects of heart and genitourinary tract, abnormal dermatoglyphic findings, short metacarpals or metatarsals, and "dysmorphic" hips. Various characteristics change with age. The faces becomes thin and asymmetric? .7 Hypotonia disappearg ,8 and hyperactive reflexes develop? The cry usually disappears or changes chaxacter, ml Hypertelorism and micrognathia are not as apparent. Older patients may exhibit premature greying, optic atrophy, strabismus, scoliosis, small wings of the ilia, large frontal sinuses, and awkward, shuffling gaits. 7 Almost all cases exhibit severe mental, growth, and motor retardation. ~° Breg et alJ report dental malocclusions in adults consisting of micrognathia, flaring of anterior teeth, overbite, openbite and local malalignments. Analysis of patients’ pictures indicates Breg probably used the term overbite to describe marked overjet. The presence of high arched palate is variableY Premature eruption of second permanent molars is reported in one case2 Although some patients survive to adulthood) ,~ most patients die in infancy due to severe respiratory and feeding problems2 Diagnosis is based on clinical features, abnormal crying during infancy, chromosomal studies, and dermatoglyphic features. Diagnosis based soley on clinical features is difficult in some cases due to phenotypic variability and to characteristics changing with age. Clinical features are used, however, as indications for confLrmatory chromosomal studiesY Cri du chat syndrome is usually attributed to a partial deletion, either terminal or interstitial, of the short arm of chromosome 57 in the area of p14 to p15 band?~ The most commonly reported cause is de novo deletion occurring in approximately 85 percent of the cases, m~ There are eight reported cases of ring chromosome 5. u,l~ Ring chromosomes result when deletions occur at the proximal and distal ends of the chromosome and the two broken ends fuse. 1~ Rings may not be present in all cells of affected individuals, may break into smaller pieces (ring products), or may contain more than one centromereY Rings that look alike may not be alike due to different amounts of chromosomal deletions. ~ Phenotype may be affected by the presence and stability of a ring,~ the translocation of chromosome 5 segments to other chromosomes) ~.~ the translocation of other chromosomes onto chromosome 5, ~ or by varying amounts of deletion of chromosome 5. Patients with ring chromosome 13, for example, appear to fall into three clinical syndromes with some overlapping features depending on how much of the ring is lost in the major cell line. ~ There is, however, little information about ring chromosome 5. Clinical characteristics of patients with ring chromosome 5 are compared in this paper for better understanding of the influence of a chromosomal ring information on cri du chat. PEDIATRIC DENTISTRY: Volume 3, Number 4 329