Letter to the Editor

Supernumerary Ring Chromosome 5 Identifiedby FISH

To the Editor:

We read with interest the review article by Dr. Crolla[1998] which stated that supernumerary marker chro-mosomes from all the human autosomes except chro-mosome 5 have been reported. We therefore describe apatient with a supernumerary ring chromosome 5.

The patient, a boy, was the only child of healthy,nonconsanguineous Japanese parents, both age 31 atthe time of his birth. The patient was born at 39 weeksof gestation: He weighed 2,540 g (−1.7 SD), his lengthwas 47.6 cm (−1.1 SD), and his OFC was 32.8 cm (−0.5SD). He had congenital stridor due to laryngomalacia,and telecanthus, low nasal bridge, hypoplastic colu-mella, preauricular tag, and high-arched palate. He satalone at age 8 months and walked at 17 months. Hetwice had febrile convulsions. Computed tomography ofthe brain was normal as were fundi. At age 3 2/12years, his height was 97.4 cm (+0.8 SD), weight was15.7 kg (+0.9 SD), and OFC was 50.5 cm (+0.5 SD). Hespoke no meaningful words.

The patient had a mosaic supernumerary ring chro-mosome with GTG banding from peripheral lympho-cyte culture (Fig. 1). The ring chromosome was nega-tive for both NOR and distamycin A/DAPI staining.The chromosomes of the parents were normal. Step-wise FISH analysis of the ring chromosome wasperformed using whole chromosome paint probes (On-cor) numbers 2, 4, 5, 7, 8, 10, 11, 12, 17, and 20 untilthe chromosomal assignment was made. The ringwas identified as 5 using the whole chromosome paint5 and the alpha-satellite probe for chromosomes 1/5/19.

His karyotype was thus 47,XY,+mar de novo[24]/46,XY[26].ish r(5)(wcp5+,D1Z7/D5Z2/D19Z3+).

REFERENCECrolla JA. 1998. FISH and molecular studies of autosomal supernumerary

marker chromosomes excluding those derived from chromosome 15: II.Review of the literature. Am J Med Genet 75:367–381.

Mitsuo Masuno*Kiyoshi ImaizumiTakuma IshiiJunko KimuraYoshikazu KurokiDivision of Medical GeneticsKanagawa Children’s Medical CenterYokohama, Japan

*Correspondence to: Mitsuo Masuno, M.D., Division of MedicalGenetics, Kanagawa Children’s Medical Center, 2-138-4 Mutsu-kawa, Minami-ku, Yokohama 232-8555, Japan.

Received 9 October 1998; Accepted 26 January 1999

Fig. 1. Partial G banded karyotype of the propositus, showing an extraring chromosome 5.

American Journal of Medical Genetics 84:381 (1999)

© 1999 Wiley-Liss, Inc.