"Pure" monosomy 21 pter leads to q21 in a girl born to a couple 46,XX,t(14;21)(p12;q22) and 46,XY,t(5;18)(q32;q22).

A two-year-old girl with a "pure" 21pter leads to q21 monosomy secondary to a 3:1 segregation of a maternal translocation t(14;21)(p12;q22) is described. The father's karyotype was 46,XY,t(5;18)(q32;q22). This observation permits to further delineate the 21q proximal monosomy syndrome and to comment the very rare finding of a couple in which both partners have different reciprocal translocations.

Partial trisomy 1q and monosomy 18q due to a de novo t(1;18)(q25;q23).

A two-year-old girl trisomic for the segment 1q25 leads to qter and partially monosomic for band 18q23 as a consequence of a de novo t(1;18)(q25;q23) is reported. Most of the proposita's clinical findings have been described in the 1qter trisomy and some others in the 18q monosomy. This observation is interpreted as additional evidence of epi-, iso-, and hypostatic interactions at the chromosomal level.

Trisomy 22q12 leads to qter: "aneusomie de recombinaison" of a pericentric inversion.

A 10-day-old girl affected with 22q12 leads to qter "pure" trisomy as a consequence of recombination within a maternal pericentric inversion (22)(p13q12) is described. A phenotypical comparative analysis reveals that the proposita's phenotype is strikingly similar to that of the trisomy 22 syndrome. Arylsulphatase-A activity was above normal levels and interpreted to be the result of a triple dosage of the gene, whose localization would be within the 22q12 leads to qter segment.

Partial trisomy and monosomy 21 in an infant with an unusual de novo 21/21 translocation.

A 3-month-old boy with a 46,XY,--21,+t(21;21)(pter leads to q22.3::q22.3 leads to q11::p11 leads to pter) karyotype, implicating trisomy for the 21q11 leads to 21q22.

Malformed genitalia in the 47,XYY genotype.

A 5 10/12 year-old boy with a 47,XYY karyotype, micropenis, scrotal hypospadias and right testicular regression is described. Normal for age basal plasma testosterone levels which increased after hCG stimulation were interpreted as an adequate response of the left testicular Leydig cells. The review of similar cases did not permit definite conclusions concerning the relationship between the abnormal genitalia and the XYY karyotype.

Some clinical and cytogenetic observations on a ring chromosome 13 (p11 q34).

A girl of 9-10/12 years of age with 46,XX,r(13)(p11q34) karyotypes was studied. She presented some clinical and radiological features, such as pectus excavatum, scalp alopecic area, 12th rib agenesis, hypoplastic pelvis, small gluteal pits and hypoplasia of the external genitalia in a female, which have never been previously described in other cases with ring 13 chromosomes. Cytogenetically, in vivo and in vitro viability of complete monosomic and partially trisomic and tetrasomic cells was found.

De novo partial trisomy of chromosome 18(pter yields q11:). Some observations on the phenotype mapping of chromosome 18 imbalances.

An infant with a partial trisomy 18(pter yields q11:) is described. The patient's phenotype consists of many features of complete trisomy 18. The findings are compared with those from similar cases reported in the literature permitting to conclude that 18q121-q122 segment is the "critical" zone which when trisomic, causes the severe stigmata (inner organ malformations and early death) of the complete trisomy 18.