Ring chromosome 7: report of the fifth case

Bilateral Cleft Lip and Palate in Ring Chromosome 7 Syndrome: A Case Report and Review of Clinical Characteristics

This report presents a case of ring chromosome 7 syndrome with bilateral cleft lip and palate. A four-year-old boy presented with bilateral cleft lip and palate, microcephaly, clenched toes, cafe-au-lait spots, a history of epilepsy, and severe intellectual disability. Genetic karyotyping revealed 46 XY r(7) (p22q36). His cheiloplasty and delayed palatoplasty were successful. A review of 22 previous r(7) patients revealed that 22.7% had cleft lip and/or palate. This case demonstrates the importance of a multidisciplinary evaluation for cleft patients, particularly those with syndromic features and global developmental delay.

Molecular cytogenetic analysis and clinical manifestations of a case with de novo mosaic ring chromosome 7

AIM

Clinical and molecular cytogenetic investigations of a newborn girl exhibiting facial dysmorphism with developmental delay.

METHODS

Phenotypic evaluation was first applied to examine the proband's developmental status. Computed tomography and colour transcranial Doppler were used then to investigate her brain structure and function. Subsequently, chromosomal abnormalities were examined by karyotyping and fluorescent in situ hybridization was performed to investigate size of fragments lost at the two distal ends of the ring chromosome 7. In addition, multicolour banding was applied to rule out structural rearrangement occurs in between the ring chromosome 7.

RESULTS

The proband was born with mosaic supernumerary ring chromosome 7, without a normal karyotype detected in the peripheral blood lymphocytes. The distal arm of chromosome 7p (at least 255 kb from the telomere) was part of an extra ring chromosome 7. In addition, the distal arm of 7q, at least 8 kb from the telomere, was missing. There was no other chromosomal rearrangement detected by multicolour banding.

INTERPRETATION

This is the 19th reported case of complete ring chromosome 7 mosaicism and the first survived case with mosaic supernumerary ring 7 without a normal karyotype detected in the peripheral lymphocytes.

Ring chromosome 7 in an Indian woman

BACKGROUND

Ring chromosome 7 [r(7)] is a rare cytogenetic aberration, with only 16 cases (including 3 females) reported in the literature to date. This is the first reported case of r(7) from India.

METHOD

Clinical and cytogenetic investigations were carried out in an adult female with microcephaly and intellectual disability.

RESULTS

Ring chromosome 7 was observed in 10% of the metaphases (46,XX,r(7)/46,XX). The clinical findings revealed microcephaly, growth delay, and dark pigmented naevi.

CONCLUSION

The mosaicism for a chromosomal anomaly is an under-recognised cause of intellectual disability.

Somatic mosaicism of chromosome 7 in a highly proliferating melanocytic congenital naevus in a ring chromosome 7 patient

Ring chromosome 7 is a rare but well documented chromosomal aberration in man. So far at least 14 cases have been reported in the literature showing a variable but distinct pattern of phenotypic characteristics in affected individuals. Besides others, skin findings as pigmented naevi are especially frequent. Loss of chromosomal material from the terminal chromosome arms in the structurally abnormal ring chromosome 7 as well as somatic mosaicism with loss or gain of chromosome 7 has been suggested to be responsible for the clinical symptoms. We now report another case of a ring chromosome 7 in a 14-year-old boy with multiple remarkable congenital naevi, where we could demonstrate for the first time somatic mosaicism showing significant gain of chromosome 7 within a highly proliferating melanocytic congenital naevus (MCN).

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

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.

Ring chromosome 7 and sacral agenesis

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.

Microcephaly with chorioretinal degeneration

PURPOSE

To describe the ophthalmologic findings and electroretinograms in patients with microcephaly and chorioretinal degeneration.

METHODS

We reviewed the hospital records of 20 patients with microcephaly that was not part of a recognizable syndrome prior to initial referral to the institutional consultative practice of one of the authors (RGW). Twelve patients, all from separate families, were diagnosed as having microcephaly with chorioretinopathy. Ten of these patients had ISCEV-standard electroretinograms (ERG).

RESULTS

No family history of microcephaly or retinal degeneration was found in any of our patients. Three patients had another family member with mental retardation. Three of the 12 were compatible with the autosomal dominant form of microcephaly with chorioretinopathy (MIM 156590), possibly as a new mutation. Eight patients, who had fundus findings of retinitis pigmentosa, were similar to the autosomal recessive form of microcephaly with chorioretinal degeneration (MIM 251270). The ERGs were moderately to severely subnormal for responses of both rods and cones. The retinal findings varied from no pigmentary changes, pigment clumping and bone spicules, pigmentary granularity, bull's eye maculopathy, choroidal and retinal atrophy, to lacunar depigmentation. Mental retardation was mild to profound. The abnormal findings from MRI/ CT brain scans (8 patients) were cerebellar atrophy (2), agenesis of cerebellar vermis (1), cortical atrophy (1), and pachygyria (1). Dysmorphic features were present in most patients. Chromosome studies were normal, except for one patient with ring chromosome 14.

CONCLUSIONS

Although the patients reviewed in this study represent a heterogeneous group of disorders, ocular abnormalities, especially retinal degeneration, are frequent among patients with microcephaly.

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

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).

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

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.

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

We report on a boy with ring chromosome 7 who had severe mental retardation, growth failure, microcephaly, cleft lip and palate, café-au-lait spots, 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 semilobar holoprosencephaly. In addition, heterotopic Purkinje cell clusters 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.