Two patients with monosomy for the distal portion of the short arm of chromosome 3 are described. Chromosome analysis on prometaphase cells demonstrated a karyotype of 46,XX,del(3) (p25.3) in one patient and 46,XX,r(3)(p26.1q29) in the other. The former patient showed characteristic clinical manifestations of the 3p- syndrome, including growth failure, mental retardation, microcephaly with a flat occiput, triangular face, synophrys, blepharoptosis, hypertelorism, broad and flat nose, long philtrum, down-turned mouth, micrognathia, apparently lowset and malformed ears, fingers abnormalities, and deafness. The latter patient had a nonspecific phenotype with mental retardation, growth failure and microcephaly. Karyotype-phenotype comparisons in the present cases and 16 previously reported cases with deficiency of the distal portion of 3p suggests that deficiency of the 3p25.3 band is critical to produce the main clinical manifestations of the del(3p) syndrome.

Loss of the 3p25.3 band is critical in the manifestation of del(3p) syndrome: karyotype-phenotype correlation in cases with deficiency of the distal portion of the short arm of chromosome 3.

This paper reports two patients with a ring 22 chromosome which has been confirmed by Q-banding. The literature contains 19 patients with a ring G-group chromosome which has been shown by chromosome banding to be a ring 22. The most commonly reported features in affected patients have included: retardation with disproportionate verbal delay, reduced head circumference, hypotonia, unsteady gait, large ears with abnormal configuration, and epicanthic folds. The importance of these, as well as other, less often noted findings, is discussed in relation to a possible r(22) syndrome.

Phenotypic correlations in patients with ring chromosome 22.

Four cases having mosaicism for a small marker or ring [45,X/46,X,+mar or 45,X/46,X,+r] chromosome were ascertained following cytogenetic studies requested because of minor anomalies (cases 1, 3, and 4) and/or short stature (cases 2 and 4). While all 4 cases had traits typical of Ullrich-Turner syndrome (UTS), cases 1, 3, and 4 had manifestations not usually present in UTS, including unusual facial appearance, mental retardation/developmental delay (MR/DD) (cases 3 and 4), and syndactylies (case 1). Using fluorescence in situ hybridization (FISH), each of the markers in these 4 cases was identified as having been derived from an X chromosome. Replication studies demonstrated a probable early replication pattern for the mar/r(X) in cases 1, 3, and 4, while the marker in case 2 was apparently late replicating. To date, 41 individuals having mosaicism for a small mar/r(X) chromosome have been described. Interestingly, most of the 14 individuals having a presumedly active mar/r(X) demonstrated clinical findings atypical of UTS, including abnormal facial changes (11) and MR/DD (13). MR was noted most frequently in those cases having at least 50% mosaicism for the marker or ring. In contrast, atypical UTS facial appearance or MR/DD was not noted in 14 of the 16 casesmore » with UTS who carried a probable late replicating marker or ring. In conclusion, although the phenotype of 45,S/46,X, mar/r(X) individuals appears to be influenced by the genetic content and degree of mosaicism for the mar/r(X), the most significant factor associated with MR/DD appears to be the activity status of the mar/r(X) chromosome. Thus, our 4 cases provide further support for the hypothesis that a lack of inactivation of a small mar/r(X) chromosome may be a factor leading to the MR and other phenotypic abnormalities seen in this subset of individuals having atypical UTS. 46 refs., 6 figs., 3 tabs.« less

Mental retardation and Ullrich‐Turner syndrome in cases with 45,X/46,X,+ mar: Additional support for the loss of the X‐inactivation center hypothesis

A patient with clinical features of Turner syndrome and a 45,X karyotype in repeated blood cultures was re-evaluated when she spontaneously entered puberty. A ring X cell line was found in a small proportion of fibroblasts. A review of 35 previously published ring X cases is presented. All are mosaic, the major cell line in most cases being 45,X. There is wide variation in the frequency with which the abnormalities associated with Turner syndrome are found in these patients. All have short stature. Some are sexually developed and fertile. Cardiovascular anomalies are uncommon. This phenotypic variation may have at least two causes: the size of the deleted portion at each end of the X chromosome, and the relative frequency and distribution of 45,X and 46,X,r(X) cell lines in various body tissues.

Turner syndrome patients with a ring X chromosome

Data from the world literature about the pathology of the urinary system in autosomal chromosomal disorders are analyzed and compared with our own morphological investigations of this system in 63 cases of chromosomal disorders (Patau's, Edwards', Down's, Orbeli's, Wolf-Hirschhorn's syndromes, partial trisomy B and inversion of chromosome 2). The urinary system is most frequently involved in “cat-eye”, triploidy, Orbeli's, Patau's and Edwards' syndromes. All known malformations of the urinary system are observed in children with chromosomal diseases, except infantile polycystic kidney and medullary “sponge” kidney. The authors recognize specific and nonspecific abnormalities of the urinary system. Nonspecific abnormalities, as simple renal dysgenesis, may be observed in all chromosomal disorders. Specific abnormalities are found only in certain chromosomal diseases. These malformations are an excess of embryonal lobulation of the kidney with the increase of its weight and cystic changes (Patau's syndrome), crossed renal ectopy with fusion and horseshoe kidney (Edwards' syndrome), unilateral renal agenesis (Orbeli's syndrome), hypospadia (Wolf-Hirschhorn's syndrome). A possible pathogenesis of malformations of the urinary system in chromosomal disorders is discussed.

C M Berlin

Papers

Human ring chromosomes: a report of five cases.