A ring chromosome 7 was found in a 19-month-old girl with microcephaly, growth and developmental delay, multiple angiomas, and partial sacral agenesis. Absent sacrum is a frequent finding in patients with 7q terminal deletions; in fact, genes involved in the sacral agenesis are localized in 7q36. However, this anomaly was not described previously in patients with a ring chromosome 7. High resolution G-banding chromosome and fluorescence in situ hybridization (FISH) demonstrated that our patient lost this region during ring formation.

Ring chromosome 7 and sacral agenesis

The present authors report the case of a 12-year-old-boy with a de novo, non-mosaic supernumerary ring chromosome 7 associated with significant developmental delay and speech difficulty. A review of the literature identified a total of 18 cases with ring chromosomes 7 who can be classified into two groups: (1) patients with a cell line that has 47 chromosomes with a small supernumerary ring chromosome 7 resulting in partial trisomy; and (2) individuals had a cell line with a large ring chromosome replacing one of the normal chromosomes 7 resulting in partial monosomy. A comparison of clinical features in the two groups of patients showed several common features such as growth and mental retardation, and facial dysmorphism, including, ear and eye anomalies. However, patients with partial trisomy have speech difficulty as a distinguishing feature, while patients with partial monosomy have skin lesions as a cardinal feature. All the published cases of ring chromosome 7, irrespective whether they are supernumerary or normal modal number, are mosaics except for one. The present subject is the first case of a de novo, non-mosaic supernumerary ring chromosome 7.

De novo supernumerary ring chromosome 7: first report of a non-mosaic patient and review of the literature.

A ring chromosome 7 was found in an 8-year-old boy investigated on account of short stature and facial dysmorphism. He had a fair skin, almost white hair, cafe-au lait spots and many black atypical pigmented naevi. Electron microscopy of his skin revealed structural changes in melanocytes and keratinocytes, suggesting disturbed cell growth and differentiation.

Boy with a ring 7 chromosome: a case report with special reference to dermatological findings.

We report on a boy with ring chromosome 7 who had severe mental retardation, growth failure, microcephaly, cleft lip and palate, cafe-au-lait sports, nevus flammeus, and genital abnormalities, and died of pneumonia at age 20 months. On autopsy he had fusion of the anterior cerebral hemispheres, accompanied by agenesis of olfactory bulbs and tracts, closely resembling those found in semi-lobar holoprosencephaly. In addition, heterotopic Purkinje cell cluster in the cerebellar white matter, absence of pigmentation within the brainstem pigmented neurons, and severe hypomyelination in the whole brain were noted.



The patient may represent the most severe manifestation of ring chromosome 7, and this is the first detailed neuropathological report on this subject. © 1993 Wiley-Liss, Inc.

Case of ring chromosome 7: The first report of neuropathological findings

We report on a patient with ring chromosome 7 analyzed by both high-resolution mid-prophase G-banding and fluorescence in situ hybridization (FISH) resolving a subband deletion of 7q36.3 associated with the clinical manifestation of holoprosencephaly (HPE).

Sub-band deletion of 7q36.3 in a patient with ring chromosome 7: association with holoprosencephaly.

A 5-month-old girl with a ring chromosome 7 [46, XX, r(7) (p22q36)I is presented. She was the fifth and youngest patient with this chromosomal anomaly, and the first instance whose chromosomal breakpoints were determined by high resolution banding analysis, Numerous cafe-au-lait-like pigmentation spots and hypoplasia of the thenar creases were observed.

Jun Kohyama

Papers

Ring chromosome 7: report of a case.