Ring chromosome

About: Ring chromosome is a research topic. Over the lifetime, 1546 publications have been published within this topic receiving 31061 citations. The topic is also known as: supernumerary circular chromosome.

Prenatal diagnosis of ring chromosome 6.

Abstract: An amniocentesis was performed on a gravida 1, para 0 23-year-old female because of high maternal serum alpha-fetoprotein and nuchal thickening/cystic mass apparent on the fetal ultrasound. Detailed ultrasound examination revealed multiple anomalies including brain abnormalities. The fetus was found to have a mosaic female karyotype: 45,XX, - 6/46,XX,r(6) (p25q27) (62 per cent:38 per cent). This is the first report of a prenatally diagnosed case of ring chromosome 6.

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

Abstract: 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 19 th 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 10 and its clinical features.

Abstract: A 2-year-old boy with mental and growth retardation is presented; he has a 46,XY,r(10)(p15q26) chromosome complement. Five previously reported cases of ring chromosome 10 were reviewed and compared with the present case in an attempt to delineate a clinical syndrome. Since the first description, identified by Giemsa banding by Lansky et al, four other r(10) patients have been described. Their common features were mental and growth retardation, low birth weight, microcephaly, stubby nose, hypertelorism, strabismus, wide set nipples, single transverse palmar creases, undescended testes, and hypoplastic scrotum. In some of the cases congenital heart disease was present.

Ring chromosome 10 syndrome: case report and the possibility of clinical diagnosis.

Abstract: A 2-year-old boy, whose clinical abnormalities included growth retardation(3rd percentile), mild mental retardation (DQ = 67), microcephaly, hypertelorism, strabismus, prominent nasal bridge, stubby nose, pointed chin, undescended testes and hydronephrosis, had a ring chromosome 10. Using high-resolution banding technique, the breakpoints were decided at p15.3 and q26.3 of chromosome 10. The clinical features observed in this case were common in 8 other cases with ring chromosome 10 previously reported. Thus, the terminal deletion of both arms of chromosome 10 seems to be the cause of the specific clinical abnormalities. When a patient has the clinical common abnormalities above mentioned, ring chromosome 10 syndrome will be suspected before chromosome analysis.

Pseudo-bartter syndrome due to hirschsprung disease in a neonate with an extra ring chromosome 8

Abstract: Chromosome 8 is the largest chromosome found to be trisomic among live born infants [Fineman et al., 1975]. Complete trisomy 8 is a frequent cause of first trimester abortions. Live born infants usually have trisomy 8 mosaicism. Common features of this trisomy 8 ‘‘mosaicism’’ syndrome include mildto-moderate mental retardation, strabismus, osseous and soft tissue abnormalities, lowset and/or malformed ears, broad bulbous nose, palate deformity, various types of congenital cardiovascular disorders, hydronephrosis, cryptorchidism and characteristic dermatoglyphics. Phenotype, due to the mosaic condition, ranges fromnormal to variable expression of congenital anomalies [Fineman et al., 1975; Matheson et al., 2003; Le Caignec et al., 2004]. The supernumerary chromosome in a trisomic condition may also be a ring chromosome. They originate from breakage in both arms of the same chromosome with subsequent fusion of the open ends. This condition leads to congenital anomalies overlapping with trisomy 8 syndrome as described above [Demori et al., 2004]. Hirschsprung disease (HD) is the main genetic cause of functional intestinal obstruction and is associated with a chromosomal abnormality in 12% of cases. Trisomy 8 mosaicism is amongst the chromosomal abnormalities to which HD is occasionally associated [Amiel and Lyonnet, 2001; Godbole 2004]. HD is characterized by the absence of parasympatic intrinsic ganglion cells in the submucosal and myenteric plexuses and leads to intestinal [Amiel and Lyonnet, 2001; Godbole 2004]. We describe a patient with pseudo-Bartter syndrome due to HD in a neonate with supernumerary ring chromosome 8 (47,XXþ r(8)/46,XX). A 21-year-old, G 1 P 0, Turkish women delivered vaginally at 32 2/7 weeks’ gestation because of irrepressible labor. Serial fetal ultrasounds were normal except for polyhydramnios. The patient, a female infant was born and was intubated soon after birth because of breathing difficulties and bradycardia. Growth parameters were the following: birth weight 2.022 g (50–75th centile), birth length 44 cm (75–90th centile) and birth head circumference 30 cm (25–50th centile). She improved and was extubated after 24 hr. Clinical findings consisted of facial dysmorphism (expressionless facies, sloping forehead, hypertelorism, downslanting palpebral fissures, flat nasal bridge with apex nasi bulbous, and anteverted and everted lips), cleft palate, elongated thin trunk with narrow shoulders and widely spread nipples and brachydactyly (Figs. 1 and 2). There was no evidence of skeletal abnormalities clinically and radiologically. Cardiac and genital examinations were normal. Opthalmological examination did not reveal any ocular abnormalities. Cranial MRI and renal sonography were normal. Karyotype and fluorescence in situ hybridization (FISH) were performed for both child and parents. The child’s karyotype was reported 47,XXþ r(8)/ 46,XX. The supernumerary ring chromosome 8 was found in approximately 60%of her lymphocytes. The karyotype of the mother was reported 46,XX and the karyotype of the father was 46,XY. Feedings went difficult with abdominal distention, much gastric retention, gastro-intestinal stasis, and vomiting. Normal passage of stools. Persistent need for parenteral nutrition. She also demonstrated signs of hypoventilation with hypoxia.