A complex chromosome rearrangement, der(6)ins(6)(p21.1q25.3q27)inv(6)(p25.3q27), in a child with cleidocranial dysplasia.

Complex chromosome rearrangements (CCRs) are structural abnormalities involving >2 chromosomes or >3 breakpoints. It has been suggested that the probability of imbalance increases as the number of breakpoints increase. Here we report a 7-month-old, Hispanic girl presenting with cleidocranial dysplasia (CCD) who was found to have a complex chromosome rearrangement of chromosome 6.

Partial trisomy and partial monosomy resulting from a reciprocal segregating in a large family.

Partial trisomy 7p with partial monosomy 9p is a rare disorder with only 3 cases reported. Both these abnormalities i.e.

Molecular cytogenetic characterization of a unique and complex de novo 8p rearrangement.

Human chromosome 8p is prone to recurrent rearrangements with inv dup del(8p) being most common. Each of these recurrent rearrangements is associated with different clinical manifestations. Some of these recurrent rearrangements at 8p are mediated by an 8p submicroscopic paracentric inversion between the olfactory gene clusters present in one of the parents.

Do cytogenetic abnormalities precede morphologic abnormalities in a developing malignant condition?

Cytogenetic evaluation of bone marrow and neoplastic tissues plays a critical role in determining patient management and prognosis. Here, we highlight two cases in which the cytogenetic studies challenge the common practice of using hematologic and morphologic changes as key factors in malignant disease management. The first case is that of a lymph node sample from a 40-yr-old non-Hodgkin's lymphoma (NHL) patient sent for determination of disease progress.

Subtelomeric rearrangements in idiopathic mental retardation.

Objective: To estimate the frequency of subtelomeric rearrangements in patients with sporadic and non-syndromic idiopathic mental retardation (IMR).

Methods: A total of 18 IMR patients were taken for the study. Selection criteria included no known syndromes or chromosomes abnormalities and known causes of IMR.

Position effects due to chromosome breakpoints that map approximately 900 Kb upstream and approximately 1.3 Mb downstream of SOX9 in two patients with campomelic dysplasia.

Campomelic dysplasia (CD) is a semilethal skeletal malformation syndrome with or without XY sex reversal. In addition to the multiple mutations found within the sex-determining region Y-related high-mobility group box gene (SOX9) on 17q24.3, several chromosome anomalies (translocations, inversions, and deletions) with breakpoints scattered over 1 Mb upstream of SOX9 have been described.

Molecular cytogenetic characterization of a recombinant chromosome rec(22)dup(22q)inv(22)(p13q12.2).

Pericentric inversions occur at a frequency of 0.12-0.7% in humans.

A rapid and noninvasive method for detecting tissue-limited mosaicism: detection of i(12)(p10) in buccal smear from a child with Pallister-Killian syndrome.

Pallister-Killian syndrome (PKS), a rare disorder, is characterized by tissue-limited or tissue-specific mosaicism. The characteristic chromosome abnormality associated with PKS is i(12p), which is seen predominantly in skin fibroblast cultures. Diagnosis of i(12p) has been carried out on buccal smears before and was shown to be an easy and feasible method.

Molecular cytogenetic characterization of a de novo unbalanced translocation leading to trisomy 17q25-->qter and monosomy 18p11.3-->pter in a girl with dysmorphic features.

An 18-year-old, gravida 1 underwent percutaneous umbilical blood sampling (PUBS) because of positive triple screen, oligohydramnios and markedly short fetal bones. Chromosome analysis showed an abnormal chromosome 18 with unidentified chromatin at the end of the p-arm. Parental karyotypes were normal.

Prenatal diagnosis of a fetus with unbalanced translocation (4;13)(p16;q32) with overlapping features of Patau and Wolf-Hirschhorn syndromes.

Wolf-Hirschhorn syndrome (WHS) and Patau syndrome are two of the most severe conditions resulting from chromosome abnormalities. WHS is caused by a deletion of 4p16, while Patau syndrome is caused by trisomy for some or all regions of chromosome 13. Though the etiologies of these syndromes differ, they share several features including pre- and postnatal growth retardation, microcephaly, cleft lip and palate, and cardiac anomalies.

Chromosome 13q neocentromeres: molecular cytogenetic characterization of three additional cases and clinical spectrum.

We report three new cases of chromosome 13 derived marker chromosomes, found in unrelated patients with dysmorphisms and/or developmental delay. Molecular cytogenetic analysis was performed using fluorescence in situ hybridization (FISH) with chromosome-specific painting probes, alpha satellite probes, and physically mapped probes from chromosome 13q, as well as comparative genomic hybridization (CGH). This analysis demonstrated that these markers consisted of inversion duplications of distal portions of chromosome 13q that have separated from the endogenous chromosome 13 centromere and contain no detectable alpha satellite DNA.

Unique case of mosaicism involving two morphologically similar marker chromosomes of different centric origin in a patient with developmental delay.

A five-year-old Caucasian male presented with developmental delay, minor dysmorphic features, and hyperactivity. Cytogenetic analysis showed the presence of a marker chromosome in the majority of cells analyzed. Fluorescence in situ hybridization (FISH) analyses using several alpha satellite probes, including D13Z1/D21Z1, did not reveal any signal on the marker chromosome.