An unstable ring chromosome in a female infant with hypotonia, seizures, and retarded development

Coexistence of Growth Hormone Deficiency and Pituitary Microadenoma in a Child with Unique Mosaic Turner Syndrome: A Case Report and Literature Review

Turner syndrome (TS) is a genetic disorder with phenotypic heterogeneity caused by the monosomy or structural abnormalities of the X chromosome, and it has a prevalence of about 1/2500 females live birth. The variable clinical features of TS include short stature, gonadal failure, and skeletal dysplasia. The association with growth hormone (GH) deficiency or other hypopituitarism in TS is extremely rare, with only a few case reports published in the literature. Here, we report the first case of a patient with mosaic TS with complete GH deficiency and pituitary microadenoma, and we include the literature review. During the work-up of the patient for severe short stature, three GH provocation tests revealed peak GH levels of less than 5 ng/mL, which was compatible with complete GH deficiency. Sella magnetic resonance imaging showed an 8 mm non-enhancing pituitary adenoma with mild superior displacement of the optic chiasm. Karyotyping revealed the presence of ring chromosome X and monosomy X (46,X,r(X)/45,X/46,X,psu dic r(X;X)), which indicated a mosaic TS. It is important to consider not only chromosome analyses in females with short stature, but also the possibility of the coexistence of complete GH deficiency accompanying pituitary lesions in TS. In conclusion, the present study reports the first case of GH deficiency and pituitary adenoma in a patient with rare mosaic TS, which extends the genotype-phenotype spectrum for TS.

Molecular cytogenetic characterization of two Turner syndrome patients with mosaic ring X chromosome

PURPOSE

In the present study, we reported two cases of TS with mosaic ring X chromosome showing common clinical characteristics of TS like growth retardation and ovarian dysfunction. The purpose of the present study was to cytogenetically characterize both cases.

METHODS

Whole blood culture and G-banding were performed for karyotyping the cases following standard protocol. Origin of the ring chromosome and degree of mosaicism were further determined by fluorescence in situ hybridization (FISH). Breakpoints and loss of genetic material in formation of different ring X chromosomes r (X) in cases were determined with the help of cytogenetic microarray.

RESULTS

Cases 1 and 2 with ring chromosome were cytogenetically characterized as 45, X [114]/46Xr (X) (p22.11q21.32) [116] and 45, X [170]/46, Xr (X) (p22.2q21.33) [92], respectively. Sizes of these ring X chromosomes were found to be ~75 and ~95 Mb in cases 1 and 2, respectively, using visual estimation as part of cytogenetic observation. In both cases, we observed breakpoints on Xq chromosome were within relatively narrow region between Xq21.33 and Xq22.1 compared to regions in previously reported cases associated with ovarian dysgenesis.

CONCLUSIONS

Our observation agrees with the fact that despite of large heterogeneity, severity of the cases with intact X-inactive specific transcript (XIST) is dependent on degree of mosaicism and extent of Xq deletion having crucial genes involved directly or indirectly in various physiological involving ovarian cyclicity.

Chromosomal mosaicism: a follow-up study of 39 unselected children found at birth

The changes of chromosomal mosaicism are examined in a sample of 39 children. A trend towards an increase in the percentage of normal cells was detected.

Severe anomalies associated with ring chromosome 7

A newborn infant with the polyasplenia sequence, intrauterine growth retardation, cutaneous nevi, and minor anomalies was found to have mosaicism for ring chromosome 7. This patient's anomalies are markedly different from those of previous patients reported with this cytogenetic anomaly.

A fourth case of ring chromosome 7

An 8-year-old child with a ring chromosome 7 is presented, the first female and the fourth such individual to be described. The associated anomalies were rather benign: she presented with short stature, minor skeletal alterations, and normal intelligence. The only truly striking feature was the presence of multiple large, pigmented naevi, suggestive of a hamartomatous origin, but unlike those typical of any particular syndrome. Though other ring 7 patients have had naevus flammeus, and one had café-au-lait spots, our proband is the first with an anomaly of chromosome 7 to have such extensive lesions. These four cases of ring 7, which show great phenotypic variation, are reviewed, and the clinical presentation of the proband is also compared with that of patients suffering from terminal, interstitial and translocation-derived 7p and 7q deletions. The formation and behavior of ring chromosomes are discussed, as are the cytogenetic factors which may influence their phenotypic expression.

Mosaicism for an extra small ring chromosome

A new case for mosaicism for an extra small ring chromosome is described in a 13-year-old girl with minimal phenotype anomalies and moderate mental retardation. The origin of the extra chromosome could not be determined either cytogenetically or clinically. The present case is compared with six similar cases in the literature.

Abnormal skin fibroblast cytogenetics in four dysmorphic patients with normal lymphocyte chromosomes

Four patients with features suggestive of chromosome disorders but with normal lymphocyte karyotypes were found to have chromosome aberrations in skin fibroblast karyotypes. Although mosaicism for chromosome abnormalities in lymphocyte cultures is common, apparent restriction of mosaicism to one tissue is unusual. We suggest that after examination of lymphocyte karyotypes, certain patients warrant cytogenetic evaluation of a second tissue, usually cultured skin fibroblasts.

Leprechaunism with mosaicism 46, XX/47, XX extra ring chromosome

A case of leprechaunism with a chromosomal abnormality is reported. The patient was a female infant, born to healthy, consanguineous young parents. Her course was one of extreme marasmus, with death at 3 months of age. She presented the classical features of the syndrome and chromosome mosaicism 46, XX/47, XX, +r(?). It was not possible to identify the origin of the extra ring chromosome. It is difficult to establish the role of such a cytogenetic finding in the aetiology of the syndrome.

Cytogenetics of 50 patients with mental retardation and multiple congenital anomalies and 50 normal subjects. Madison blind study IV

The chromosomes of 50 idiopathic mentally retarded patients with at least three other anomalies and 50 normal subjects were analyzed from randomized coded slides. The chromosomally abnormal cases were also studied by means of Q-banding. Seven of the patients showed a chromosome anomaly. Two had an extra G-like chromosome, which in case M99 consisted mainly of 16p (he had also a small Y chromosome shared by his father and brother), and in case M8 of 9p. The mother and sister of M99 were balanced translocation carriers. Case M18 (published separately) has approximately half of 12p deleted. Case M60 had a deletion of 20q and trisomy for a segment which most probably came from 7p. Case M49 had a deletion of 1p and increased centric heterochromatin in 1q: the latter abnormality was shared by the father and a sister. Case M83 displayed low-grade mosaicism for cells with an extra small ring of unknown origin. Case M38 had the brightly fluorescent distal part of the Y chromosome duplicated, and the father had the same chromosome. In the five first cases the phenotype was presumably caused by the chromosome anomaly, and in the mosaic this is a possible cause. In the normal subjects, two persons had minor chromosome anomalies: case M68 had a pericentric inversion in the Y chromosome, which was found also in the father and the brother, and case M10 had a telocentric no. 21. Three of the patients (M18, M49 and M99) can be regarded as type specimens for new syndromes in the sense that the chromosome anomalies causing the respective phenotypes have been identified for the first time.

Mental retardation and congenital malformations associated with a ring chromosome 6

A boy, in whom a ring chromosome 6 was found, presented with mental retardation and odd facies. He had a small head, bilateral epicanthus, broad nasal bridge, low set prominent ears, short neck and clasped thumbs. The ring chromosome was identified by the ASG banding technique.

Monozygotic twins with ring chromosome 22

Mentally retarded and monozygous twin sisters, with little physical abnormality, are described. Each twin carried a small ring chromosome, identified as a number 22.

Multiple congenital anomalies associated with a ring-D chromosome

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Ring chromosomes in two infants with congenital malformations

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A translocation t (Bq+: Cq-) in a West Indian family and a report of a second family showing a possible long arm group B translocation

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Ring chromosome 18 in a patient with multiple anomalies

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