It has been suggested previously that patients with terminal deletions of chromosome 10q have a recognizable phenotype including a characteristic facial appearance combined with other abnormalities including mental retardation, cardiac and anogenital anomalies. We report the largest published series of new cases of terminal 10q deletion, including eight familial and four de novo cases and three cases with interstitial deletions involving chromosome bands 10q25.2-26.3. The deleted regions were defined by FISH using YAC probes, as well as standard karyotyping. The most consistent clinical features in our cases are cranial anomalies including facial asymmetry, prominent nose and nasal bridge, prominent ears, thin upper lip, along with growth retardation, developmental delay, and digital abnormalities. Visceral abnormalities were only identified in a small number of the patients, with renal involvement in three cases and structural cardiac malformations in two others. Learning difficulties of varying severity were found in 11 cases and behavioral problems described in four. Candidate genes for behavioral and learning difficulties within the deleted region include Calcyon. Other genes in the region that might have a role in causing the phenotype include the genes coding for fibroblast growth factor receptor type 2 (FGFR2) and C-terminal binding protein 2 (CTBP2).

Deletion of the distal long arm of chromosome 10; is there a characteristic phenotype? A report of 15 de novo and familial cases

A patient is described with multiple congenital anomalies and probable tetrasomy 18p resulting from an extra i(18p) in an otherwise normal karyotype. Review of ten previously reported i(18p) cases allowed the tentative characterisation of a tetrasomy 18p syndrome.

https://jmg.bmj.com/content/jmedgenet/20/2/144.full.pdf

Tetrasomy 18p: tentative delineation of a syndrome

Ring chromosome 10—r(10)—is a rare disorder, with 14 cases reported in the literature, but only two with breakpoint determination by high-resolution techniques. We report here on two patients presenting a ring chromosome 10, studied by G-banding, fluorescent in situ hybridization (FISH), multiplex ligation-dependent probe amplification (MLPA) and SNP-array techniques, in order to investigate ring instability and determine breakpoints. Patient 1 showed a r(10)(p15.3q26.2) with a 7.9 Mb deletion in 10q26.2-q26.2, while patient 2 showed a r(10)(p15.3q26.13) with a 1.0 Mb deletion in 10p15.3 and a 8.8 Mb deletion in 10q26.13-q26.3, both unstable. While patient 1 presented with clinical features usually found in patients with r(10) and terminal 10q deletion, patient 2 presented characteristics so far not described in other patients with r(10), such as Dandy-Walker variant, osteopenia, semi-flexed legs, and dermal pigmentation regions. Our data and the data from literature show that there are no specific clinical findings to define a r(10) syndrome.

Ring chromosome 10: report on two patients and review of the literature

A 2-year-old boy with mental and growth retardation is presented; he has a 46,XY,r(10)(p15q26) chromosome complement. Five previously reported cases of ring chromosome 10 were reviewed and compared with the present case in an attempt to delineate a clinical syndrome. Since the first description, identified by Giemsa banding by Lansky et al, four other r(10) patients have been described. Their common features were mental and growth retardation, low birth weight, microcephaly, stubby nose, hypertelorism, strabismus, wide set nipples, single transverse palmar creases, undescended testes, and hypoplastic scrotum. In some of the cases congenital heart disease was present.

https://jmg.bmj.com/content/jmedgenet/20/2/142.full.pdf

Ring chromosome 10 and its clinical features.

A 2-year-old boy, whose clinical abnormalities included growth retardation(3rd percentile), mild mental retardation (DQ = 67), microcephaly, hypertelorism, strabismus, prominent nasal bridge, stubby nose, pointed chin, undescended testes and hydronephrosis, had a ring chromosome 10. Using high-resolution banding technique, the breakpoints were decided at p15.3 and q26.3 of chromosome 10. The clinical features observed in this case were common in 8 other cases with ring chromosome 10 previously reported. Thus, the terminal deletion of both arms of chromosome 10 seems to be the cause of the specific clinical abnormalities. When a patient has the clinical common abnormalities above mentioned, ring chromosome 10 syndrome will be suspected before chromosome analysis.

Ring chromosome 10 syndrome: case report and the possibility of clinical diagnosis.

A teenage girl with growth and mental retardation, urinary tract and eye abnormalities was found to have an r(10)(p15q26) in blood cells. Quantitative evaluation of seven red cell enzymes including three (HK1, TGOS, PGAMA) known to be on chromosome 10, gave normal values.

J L Taillemite

Papers

[Ring chromosome 10: 46,XX,r(10)(p15q26)].

Chromosome 10 en anneau: 46,XX,r(10)(p15q26).