Abnormal chromosome complement resulting from a familial inversion of chromosome 2

2q34-qter duplication and 4q34.2-qter deletion in a patient with developmental delay

The 2q3 duplication and 4q3 deletion syndromes are two conditions with variable phenotypes including Pierre-Robin sequence (PRS), limb anomalies, congenital heart defects (CHD), developmental delays and intellectual disabilities. We describe a patient born to a mother with a balanced t(2; 4) translocation who combines both a 2q34-qter duplication and a 4q34.2-qter deletion through inheritance of the derivative chromosome 4 (der(4)). He showed developmental delay, growth retardation, hearing problems, minor facial and non-facial anomalies, such as bilateral fifth finger shortness and clinodactyly, but no PRS or CHD. The comparison of his features with those of 46 and 65 published cases of 2q3 duplication and 4q3 deletion, respectively, allows us to further restrict the size of the proposed critical intervals for PRS and CHD on chromosome 4.

Unrelated patients with a rearrangement of chromosome 2 causing duplication of 2p23 and deletion of 2q37

We describe two unrelated patients who each have a similar chromosome 2 with duplication of 2p23 to pter, and deletion of 2q37 to qter. In one, the abnormality was derived from his mother with a pericentric inversion. Both individuals have frontal bossing; abnormally formed, low set and posteriorly rotated ears; redundant nuchal skin; inversion of the nipple(s); fleshy fingertips with prominent pads; a sacral dimple; significant developmental delay/mental retardation; and G-tube dependency. Most of these features are present in previously described individuals with either duplication of the 2p terminus or deletion of the 2q terminus. This report is the first that documents postnatal viability of individuals with concurrent duplication of 2p and deletion of 2q, and also generation of this imbalance through rearrangement of a maternally inherited pericentrically inverted 2. This report should be considered in the reproductive counseling of individuals with pericentric inversions of chromosome 2.

An unusual reciprocal translocation detected by subtelomeric FISH: Interstitial and not terminal

An 11-month-old boy with a pattern of dysmorphic signs, an atrial septal defect, right inguinal hernia, bilateral undescended testes, bilateral urinary reflux, right renal dysplasia, and developmental delay had an abnormal chromosome 11 with additional material of unknown origin attached to the long arm in his karyotype. The paternal karyotype was normal 46,XY, while the mother's karyotype was 46,XX,t(2;11)(q35;q24.2). Thus, a reciprocal terminal exchange was assumed resulting in duplication of distal 2q material and a small subterminal 11q deletion. However, application of subtelomeric fluorescence in situ hybridization (FISH) probes indicated that the translocation was not a terminal reciprocal exchange, but was interstitial at least for one of the chromosomes, which would be highly unusual since most interstitial translocations are non-reciprocal. Based on the results of FISH and microsatellite marker examinations, the designation of the breakpoints and thus of the deleted and duplicated segments had to be revised. The findings have implications for karyotype-phenotype correlation.

Case of partial duplication 2q3 with characteristic phenotype: rare occurrence of an unbalanced offspring resulting from a parental pericentric inversion

We report on a male infant with partial trisomy 2q (q34-->qter) resulting from a maternal pericentric inversion of chromosome 2 (p25. 2q34). The infant had clinical findings similar to the characteristic phenotype associated with a partial duplication of chromosome 2q3. Carriers of pericentric inversions of chromosome 2 have an increased risk of pregnancy loss but have only rarely been reported to have a liveborn offspring with an unbalanced chromosome constitution. This case further confirms the risks associated with a pericentric inversion of chromosome 2 and is the second report with manifestations of the trisomy 2q3 phenotype.

De novo direct duplication 2 (p12-->p21) with paternally inherited pericentric inversion 2p11.2 2q12.2

We report a 4-year-old girl with a previously undescribed de novo duplication of 2p12->2p21 on the same homologue as a paternally inherited pericentric inversion of region 2p11.2-->2q12.2, resulting in dysmorphic features, cardiac abnormality, cleft palate, respiratory problems, severe growth retardation and developmental delay. This case raises an important question--did the paternal pericentric inversion influence the occurrence of the de novo duplication?

Case report of rec(7)dup(7q)inv(7)(p22q22) and a review of the recombinants resulting from parental pericentric inversions on any chromosomes

We report a rare case of duplication for 7q22 --> 7qter and deletion for 7p22 --> 7pter, resulting from a meiotic recombination of a paternal pericentric inversion, inv(7)(p22q22). The newborn boy had the 7q trisomy syndrome. In addition, the diagnosis of chondrodysplasia punctata was made from lumbar and hand X-ray films taken soon after birth. Only two cases of rec(7)dup(7q), both in a single family, have been reported previously. We review 133 offspring with recombinations resulting from pericentric inversions on any chromosomes reported between 1981 and 1995. Of the 133 cases, 110 had a long-arm duplication and short-arm deletion, while only 23 had a short-arm duplication and long-arm deletion. In 85 of the 133 cases, the mother was an inversion carrier (five carriers had two affected offspring), and in 46, the carrier was a father (one carrier had three affected offspring). Kaiser [Hum Genet 1984;68:1-47] reviewed 63 offspring with recombinations derived from a parental pericentric inversion reported between 1972 and 1981. In both surveys, recombinations resulting from pericentric inversions of chromosomes 1, 12, 19, and Y were not found.

Deletion or triplication of the alpha 3 (VI) collagen gene in three patients with 2q37 chromosome aberrations and symptoms of collagen-related disorders

Two new cases of del(2)(q37.1) and one case of partial trp(2)(q37) are studied by FISH with cosmid probes from the COL6A3 and PAX3 genes mapped in 2q37.3 and 2q36, respectively. While the PAX3 gene dosage appeared unaffected, the COL6A3 gene was found to be deleted and triplicated, respectively. This finding could explain features of connective tissue disorders such as joint laxity and hypotonia or joint stiffness and epiphyseal dysplasia, particularly documented by congenital dislocation of the radial head. Karyotype-phenotype correlations with reference to published cases are discussed.