3 -48 Full affiliations can be seen as electronic supplementIn a search for potential infertility loci, which might be revealed by clustering of chromosomal breakpoints, we compiled 464 infertile males with a balanced rearrangement from Mendelian Cytogenetics Network database (MCNdb) and compared their karyotypes with those of a Danish nation-wide cohort. We excluded Robertsonian translocations, rearrangements involving sex chromosomes and common variants. We identified 10 autosomal bands, five of which were on chromosome 1, with a large excess of breakpoints in the infertility group. Some of these could potentially harbour a male-specific infertility locus. However, a general excess of breakpoints almost everywhere on chromosome 1 was observed among the infertile males: 26.5 versus 14.5% in the cohort. This excess was observed both for translocation and inversion carriers, especially pericentric inversions, both for published and unpublished cases, and was significantly associated with azoospermia. The largest number of breakpoints was reported in 1q21; FISH mapping of four of these breakpoints revealed that they did not involve the same region at the molecular level. We suggest that chromosome 1 harbours a critical domain whose integrity is essential for male fertility.

A 46,XY/46,XY,del(20)(ql3-+ql3.33) mosaicism was identified in a 68 year old man who had mild mental retardation and severe malformation of the limbs. The clinical findings of the patient are compared to those of the very few cases of 20q deletion published to date. (J Med Genet 1993;30:171-3) Constitutional anomalies of chromosome 20 are rare. A few cases have been reported with ring 20,' a few with complete or partial trisomy (mostly of the short arm),2 and a very few with partial deletion of the short or the long arm.3-Deletions of the long arm in particular are extremely rare.We report here an additional case of partial 20q deletion (mosaic) in a malformed man.Case report A 68 year old malformed male, of Jewish Iranian origin, was admitted to hospital after a.,1 .F road accident. He was known to be mildly mentally retarded from childhood. He had married a cousin and fathered four normal children. His wife had no record of abortions or abnormal births.On physical examination the patient had an asymmetrical face, pterygium of both eyes, a low set, malformed left ear, a prominent nasal bridge, prognathism, a short neck, and a flat occiput. Diffuse hirsutism and upper and lower limb malformations were noted. The hands were in an abducted position. On the right hand, the second and fourth digits overlapped the third, and the thumb bones were hypoplastic. On the left hand, congenital absence of the thumb was noted.X rays of the limbs showed dislocation of the radioulnar joint, deformity of the distal radius, and hypoplasia of the scaphoid and metacarpal bones of the thumb in the right arm. In the left arm, dislocation of the wrist, hypoplastic proximal radius, absence of the distal radius, and congenital absence of the thumb were noted. The right leg was normal, whereas the left one had pes cavus with toe clawing and coxa vara (figs 1 and 2).The right leg, injured in the accident, was swollen and showed a giant haematoma. During hospitalisation, lymphoedema developed in this leg. Among other studies, CT scan of both legs was performed, and showed lymphoedema secondary to the injury in the right leg. In the left leg, muscular atrophy was noted, subcutaneous and intramuscular adipose tissue replacing muscular tissue. No abnormalities were noted on neurological examination.A holosystolic murmur was heard over the cardiac apex. Electrocardiogram showed ischaemic changes in the lateral wall, but no symptoms of cardiac disease were present. Echo Doppler studies of the heart showed mild r I: Figure 1 Malformations of the patient's head and limbs.

A girl with multiple congenital anomalies and a tendency to severe pyogenic infections was found to have an interstitial deletion of chromosome band 2q14----q21. Unusual facial manifestations included enophthalmos, long philtrum, micrognathia, narrow forehead, prominent glabella, and depressed nasal bridge. Unilateral corneal clouding, with Peters-like anomaly; agenesis of the corpus callosum; brain atrophy; and heart, kidney, hand, and dermatoglyphic anomalies were additional findings. Eye anomalies were observed in five of 22 patients with deletions of chromosome 2q. In comparing these cases, it seems that deletions of bands 2q21 and 2q31 are variably associated with microphthalmia, corneal clouding, cataracts, and Peters anomaly. Measurement of protein C and interleukin-1 (IL-1) did not show a gene dose effect, but the pyogenic infections and low IgA found in this patient may reflect an abnormality of IL-1 not detectable by our methods.

A patient with pure trisomy of the short arm of chromosome 17 in 60% of the examined cells is reported. She presented a variant chromosome 1 with partial pericentric inversion and increased centromeric heterochromatin in one chromosome 17. The cytogenetic findings are discussed. The clinical findings are compared to those found in other reported cases of partial trisomy 17 and a delineation of a pure trisomy 17p attempted.

The increased spontaneous chromosomal breaks in the right colon, as opposed to the increased mutagen-induced chromosomal breaks in the left colon, might indicate that in young colon cancer patients the occurrence of right-sided colon cancer is more likely to be genetically determined, whereas in left-sided colon cancer, environmental carcinogens might play a greater role.