Chromosome 20 long arm deletion in an elderly malformed man.

Abstract

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.

Intrachromosomal insertion mimicking a pericentric inversion: Molecular cytogenetic characterization of a three break rearrangement of chromosome 20

“…The other reported cases include a larger terminal deletion (q13qter) associated with severe seizures, facial dysmorphism, and malformation of the extremities [Fraisse et al, 1981] and four interstitial deletions: q11.23q13.11 [Petersen et al, 1987], q13.11q13.33 in mosaic [Shabtai et al, 1993], q13.31q13.33 and q13.13q13.32 [Aldred et al, 2002]. These four patients had Albright hereditary osteodystrophy or clinical manifestations overlapping with this syndrome.…”

A de novo deletion of 20q11.2–q12 in a boy presenting with abnormal hands and feet, retinal dysplasia, and intractable feeding difficulty

“…To our knowledge, a total of 12 patients have been reported in the literature [Petersen et al, 1987;Shabtai et al, 1993;Aldred et al, 2002;Genevieve et al, 2005;Callier et al, 2006;Borozdin et al, 2007;Iqbal and Al-Owain, 2007]. Among them, only two cases showed the proximal q deletion (20q11-q12), not extending to q13 [Callier et al, 2006;Iqbal and Al-Owain, 2007].…”

Physical and linkage mapping of the gene for the α3 chain of type IX collagen, COL9A3, to human chromosome 20q13.3

“…The map is consistent with the NIH consensus map (1992), and places COL9A3 beyond the most recent Genethon genetic linkage map (Dib et al, 1996), thus distinguishing it as the most distal characterized gene on human chromosome 20q. Two previous reports have described patients with terminal deletions distal to 20q13.11 who exhibited severe limb malformations (Fraisse et al, 1981;Shabtai et al, 1993). These cases suggest that underexpression of COL9A3 may result in abnormal morphology of tissues expressing this gene.…”