A chromosome 13q+ in a patient with characteristics of the trisomy 13 syndrome

The phenotype in partial 13q trisomies, apropos of a familial (13;15)(q22;q26) translocation

A 12 month-old male patient with a karyotype 46,XY,-15,+der(15),t(13;15)(q22;q26)pat is presented. His stillborn sib showed malformations compatible with the 13q deletion syndrome, probably due to a 46,XY,der(13) karyotype. Phenotypic analysis of 41 cases from the literature with partial distal 13q (D13q) trisomies indicate that the segment 13q22----qter in trisomy with or without another concomitant aneusomy is sufficient to produce the majority of the trisomy 13 syndrome features, some of which (cleft palate, increased HbF and projections in PMN) are present in different non-overlapping partial 13q trisomies. About 82% of the D13q trisomies are inherited, more frequently from the mother.

The aetiology of the cat eye syndrome reconsidered

The cat eye syndrome (CES), usually ascribed to the presence of a deleted supernumerary 22 chromosome, is characterised by a typical clinical picture including anal atresia, ocular coloboma, preauricular tags or sinuses, congenital heart defects, urinary tracts anomalies, and mental and physical retardation. An analysis of published reports revealed that of the 57 reported cases, only 21 showed the complete form, and 11 had a normal karyotype. Several observations question the existence of a trisomy 22:(1) the absence of any report in living subjects of trisomy 22 arising from an inherited Robertsonian translocation; (2) the recurrent abortions in carriers of Robertsonian translocations involving chromosome 22; and (3) the existence of a syndrome, showing the same clinical features as trisomy 22, which is irrefutably dependent on a trisomy of the distal region of the 11 long arm. On the basis of a comparison of the clinical features in full trisomy 13, partial 13 trisomies, 13 rings, 13 deletions, and CES the small marker present in this syndrome is considered to be a chromosome 13 with an interstitial deletion. An attempt to map this chromosome has been made.

Anatomical studies of a boy trisomic for the distal portion of 13q

A boy trisomic for the distal portion of 13q was dissected in detail and compared to 8 cases of complete trisomy 13 previously studied in our laboratory. The comparison shows that the partial trisomy 13q case did not correspond well to a muscle phenotype based on 6 variations common trisomy 13, but rather to a larger muscle phenotype that included variations less frequently observed in complete trisomy 13. Additional cases of partial trisomy 13 must be studied before these findings can be related to specific portions of chromosome 13.

Partial trisomy 13 presumably due to recombination in an inversion heterozygote and by unequal crossing-over

Two unrelated infants with partial trisomy 13 for the distal of the long arm are described. In one, a familial pericentric inversion is present in three generations and crossing-over in the inversion loop is considered as cause of partial trisomy 13. The other showed a tandem duplication of the distal half of the long arm of chromosome 13 beyond 13q14. This is interpreted to have arisen by unequal crossing-over in mispaired synapsis. It is suggested that recombination rather than breaks is a distinctive although rare cause of human chromosomal imbalance.

Familial translocation with partial trisomy of 13 and 22: evidence that specific regions of chromosomes 13 and 22 are responsible for the phenotype of each trisomy

A newborn infant with clinical and pathological findings typical trisomy 13 and 22 syndromes had an extra chromosome which was a derivative chromosome from maternal balanced translocation affecting Nos. 13 and 22; 47,XY,+der(22),t(13:22)(q22:q12)Mat. The presence of extra specific euchromatic regions of No. 13(13q22 and/or 13q34) and No. 22 (22q11) seem to be responsible for the trisomy 13 and 22 syndromes.

Chromosome 7 short arm deletion and craniosynostosis. A 7p-syndrome

A patient with craniosynostosis and a small deletion of part of the short arm of chromosome 7 is described. A review of the literature indicates that craniosynostosis has occurred in at least four of the five infants (the fifth having microcephaly) affected by structural changes (resulting in deletion) within the terminal region of the short arm of chromosome 7.

Further delineation of the clinical picture of trisomy for the distal segment of chromosome 13: report of three cases

Three cases of partial trisomy for the distal segment of chromosome 13 are reported. Common clinical features included normal birth weight, postnatal asphyxia, convulsions, severe psychomotor retardation, normal growth, and a distinct pattern of dysmorphias consisting of trigonocephalic head with prominent metopic suture, long and markedly curved eyelashes, a stubby nose, increased distance between nose and upper lip, high-arched palate, misshapen ears with virtually absent lobules and prominent anthelices which are curved in a sharp angle, and hemangiomata. Features present in 2 cases were microcephaly, long and narrow fingers with convex nails, and hexadactyly. Two cousins were unbalanced offspring of a large family of carriers of a 9/13 translocation, whereas the third case exhibited a 13p+ chromosome which was formed de novo. The clinical features in the 3 patients are typical of the syndrome due to partial trisomy for the distal segment of chromosome 13 which shows selected and mitigated signs of full trisomy 13.