Ring chromosome 9. Case report and review of the literature

We report on a girl with ring chromosome 9, and review the 9 other cases of the literature. The main signs of this de novo chromosomal anomaly are: severe microcephaly, growth and psychomotor retardations, and heart malformations. Infectious complications occurs often. We found a decreased level of leucocyte interferon.     

Ring chromosome 16

Summary Ring chromosome 16 was found in a 33-year-old woman with mental, motor, and growth defects. Apart from a low percentage of monosomy 16 cell lines, the patient appears to have virtually all of the normal chromosome 16 genetic material at the microscopic level. Her impressive problems highlight the limitation of our ability to detect small deletions and the profound importance of the integrity of chromosome 16 in normal human development.     

Ring chromosome 15 syndrome

Summary Two new cases of ring chromosome 15 are reported. A review of the nine cases described in the literature shows that ring chromosomes 15 are associated with a rather uniform phenotype characterized by slight to moderate mental retardation, marked pre- and postnatal growth failure, triangular face, and short hands and feet.     

Ring (15) chromosome

Summary Cytogenetic studies on lymphocytes from a girl aged 3 years and 10 months revealed a ring chromosome 15. Several banding methods showed the r(15) chromosome not to have any apparent deletion of the long arm. The silver staining technique for nucleolar organizer regions showed an NOR positive region (band p12). In only a few cells was a chromosome 15 missing. The size of the r(15) was found to be constant. Comparison with 11 previous reported cases in the literature shows that the clinical manifestations in the different patients with ring chromosome 15 are constant although not clinically identifiable and it appears likely to attribute them to a significantly retarded intrauterine and postnatal growth instead of presumed deficiency in the long arm and mosaic configurations.     

Ring chromosome 4 and wolf syndrome

Summary A 5-day-old male child presenting some features of Wolf syndrome is studied. The analysis of his karyotype by usual techniques showed a ring chromosome of B group. This chromosome was present in most of the cells examined. By GTG banding it was identified as a No.4 chromosome, the karyotype being: 46,XY,r(4),(p15q35). The analysis was completed by familial cytogenetic and dermatoglyphic studies.     

Ring chromosome 13 (author's transl)]

A ring for chromosome 13 with loss of the bands p12 and q34, is reported in a person with clinical features characteristic of the loss of these specific segments.     

Ring chromosome 16: a new case

A 46,XX,r(16) "de novo" karyotype is reported in a 4 7/12-year-old girl. In spite of the mild cranio-facial dysmorphism without visceral malformations in r(16) patients, the proband's phenotype is similar to the other four previous case reports. This could support the hypothesis of a specific "r(16) syndrome".     

Ring chromosome 8 associated with microcephaly.

A two-year-old mental defective girl with microcephaly and minor dysmorphic features had a 46,XX,r(8) karyotype. Low birth weight, short stature, and mental retardation were common features in the four known patients with r(8).     

Ring chromosome 21 in a normal female

In the present paper we report a phenotypically normal woman with a ring chromosome 21 in her karyotype, who sought genetic counseling because of her previous reproductive failure and whose third, prenatally diagnosed, pregnancy resulted in the delivery of a healthy and karyotypically normal boy.     

Ring chromosome 14 in monozygotic twins]

An r(14) is observed in monozygotic twins, with psychomotor retardation and no obvious somatic malformation.     

Ring chromosome 4 mosaicism and Potter sequence

A 46,XY/46,XY,r(4) mosaicism is described in a malformed male newborn with bilateral renal agenesis. A review of the phenotypic findings in the previously reported ring chromosome 4 patients is made and the importance of the detection of chromosomal abnormalities towards the nosology of malformation sequences is discussed.     

Ring chromosome 9 in a newborn male presenting with facial dysmorphia, hypospadias and skeletal abnormalities.

A newborn male presenting with a peculiar appearance, hypertonia, a flexum attitude, hypospadias and skeletal abnormalities was found to bear a r 9 chromosome. A phenotypic distinction between early and late presenting forms is discussed.     

Ring chromosome 10 Associated with multiple congenital malformations

Summary A paracentric inversion of the short arm of chromosome 1 (inv(1)(p22p36)) is reported in a deeply mentally retarded 19-year-old girl and in her normal father.     

Ring chromosome 15: characterization by array CGH

Ring chromosome 15 [r(15)] is an uncommon finding with less than 50 patients reported. Precise genotype–phenotype correlations are problematic because of the difficulties in determining the extent of euchromatic loss, the level of mosaicism, and the influence of the timing of ascertainment. We report two discordant examples of r(15) patients. In the first case, prenatal diagnosis of a de novo r(15) was made during the second trimester: mos 46,XX,r(15)(p11.2q26)[32]/45,XX,-15[13]/47,XX,r(15)(p11.2q26)x2[3]/46,XX,dic r(15)(p11.2q26p11.2q26[1]/46,XX[2]. Postnatal follow-up revealed extremely small stature, heart defects, and developmental delay. Patient 2 was a 31-year-old short-statured female who was living independently: 46,XX,r(15)(p11q26). Both cases showed loss of the 15q subtelomeric region by fluorescence in situ hybridization (FISH). To investigate the discordance in phenotypes between the two patients, we undertook array comparative genomic hybridization (array CGH) analyses to more fully characterize the deletions associated with these otherwise structurally indistinguishable r(15) chromosomes from conventional cytogenetic analyses and fluorescence in situ hybridization (FISH) studies. By array CGH, patient 1 showed deletion of multiple contiguous clones predicting an approximately 6 Mb deletion of distal 15q. In contrast, patient 2 showed loss of just the 15q subtelomeric clone and an interstitial clone by array CGH confirming that the severity of the phenotype correlated with the size of the deletion at the molecular level. These cases illustrate the utility of array CGH characterization for determining the size of the associated deletion in ring chromosomes and for facilitating phenotype–genotype correlations.