Familial pericentric inversion of chromosome 8

The molecular mechanisms of recombinant chromosome 18 with parental pericentric inversions and a review of the literature

Chromosomal rearrangements mostly result from non-allelic homologous recombination mediated by low-copy repeats (LCRs) or segmental duplications (SDs). Recent studies on recombinant chromosome 18 (rec (18)) have focused on diagnoses and clinical phenotypes. We diagnosed two cases of prenatal rec (18) and identified precise breakpoint intervals using karyotype and chromosomal microarray analyses. We analyzed the distribution characteristics of breakpoint repetitive elements to infer rearrangement mechanisms and reviewed relevant literature to identify genetic trends. Among the 12 families with 25 pregnancies analyzed, 68% rec (18), 24% spontaneous abortions, and 8% normal births were reported. In the 17 rec (18) cases, 65% presented maternal origin and 35% were paternal. Short-arm breakpoints at p11.31 were reported in 10 cases, whereas the long-arm breakpoints were located at q21.3 (6 cases) and q12 (4 cases). Breakpoints of pericentric inversions on chromosome 18 are concentrated in p11.31, q21.3, and q12 regions. Rearrangements at 18p11.31 are non-recurrent events. ALUs, LINE1s, and MIRs were enriched at the breakpoint regions (1.85 to 3.42-fold enrichment over the entire chromosome 18), while SDs and LCRs were absent. ALU subfamilies had sequence identities of 85.94% and 83.01% between two pair breakpoints. Small repetitive elements may mediate recombination-coupled DNA repair processes, facilitating rearrangements on chromosome 18. Maternal inversion carriers are more prone to abnormal recombination in prenatal families with rec (18). Recombinant chromosomes may present preferential segregation during gamete formation.

Localization of a gene for familial patella aplasia-hypoplasia (PTLAH) to chromosome 17q21-22

Patella aplasia-hypoplasia (PTLAH) is a rare genetic defect characterized by congenital absence or marked reduction of the patella. PTLAH can occur either as an isolated defect or in association with other malformations, and it characteristically occurs in the nail-patella syndrome and in some chromosome imbalances. We report the first evidence of linkage for isolated PTLAH in an extended Venezuelan family. After exclusion of the candidate chromosome regions where disorders associated with PTLAH have been mapped, a genomewide scan was performed that supported mapping of the disease locus within a region of 12 cM on chromosome 17q22. Two marker loci (D17S787 and D17S1604) typed from this region gave maximum LOD scores >3. Accordingly, multipoint analysis gave a maximum LOD score of 3.39, with a most likely location for the disease gene between D17S787 and D17S1604. Sequencing of the noggin gene, a candidate mapping between these markers, failed to reveal any mutation in affected subjects.

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.

Natural history of the recombinant (8) syndrome

The recombinant 8[Rec(8)] syndrome [rec(8), (8qter-->8q22.1::8p23.1-->8qter] is due to a parental inv(8)(8pter-->8p23.1::8q22.1-->8p23.1::8q22+ ++.1-->8qter). All inv(8) parents we have studied were of Hispanic origin. The Rec(8) phenotype consists of a characteristic set of minor facial anomalies, cardiovascular and other major malformations, and moderate to severe mental retardation. The clinical phenotype is relatively consistent in all published cases; however the natural history of the condition has remained unknown. Retrospective and prospective information on 42 propositi, spanning a period from 5 days to 23 years, allowed us to define the natural history of this syndrome, tabulate the frequency and the evolution of phenotypic abnormalities, and share our experience with different therapeutic approaches.

Deletion of the proximal short arm of chromosome 8

We report on a 5-month-old boy with a de novo interstitial deletion of the proximal short arm of chromosome 8 (p21p11.2). He manifested bilateral cleft lip and palate, and apparent hypogonadism. Four previous case reports with similar deletions (p11.1p21) were associated with hypogonadotropic hypogonadism [Beighle et al., Hum Genet 38:113-121, 1977] and hereditary spherocytosis (HS) [Chilcote et al., Blood 6:156-159, 1987; Kitatani et al., Hum Genet 78:94-95, 1988; Lux et al., Nature 345:736-739, 1990]. Our patient has no demonstrable red blood cell abnormality, suggesting that the gene for HS is located in the region 8p11.1 to 8p11.2.

Recombinant 8 syndrome: the pool of Hispanic pericentric inversion 8 carriers expands numerically and geographically

Recombinant 8 syndrome is a well-established syndrome with mental and developmental retardation and usually severe cardiac anomalies. A carrier parent will produce affected offspring in 6% of pregnancies and carrier offspring in 53% of such pregnancies. Four New Mexican kindres ascertained by the discovery of four apparently unrelated probands with cytogenetically confirmed recombinant 8 syndrome were studied. We found that (1) recombinant 8 syndrome will soon no longer be confined to New Mexico and southern Colorado, (2) the number of persons at risk may be higher than previously considered, and (3) through proper pedigree techniques and increased professional education, most carriers can be identified.

San Luis Valley recombinant chromosome 8 and tetralogy of Fallot: a review of chromosome 8 anomalies and congenital heart disease

Tetralogy of Fallot, the most common cyanotic heart defect, has not been closely associated with a specific chromosome defect. The San Luis Valley Recombinant Chromosome 8 [SLV Rec(8)] syndrome is strongly associated with congenital heart disease, particularly tetralogy of Fallot. This article reviews SLV Rec(8) syndrome and other chromosome 8 aberrations to suggest locations for cardiogenic genes. SLV Rec(8) [rec(8),dup q,inv(8)(p23q22)] syndrome has been found in Hispanic families in the southwestern United States. Congenital heart disease is found in 93.3% of SLV Rec(8) individuals (n = 45), with tetralogy of Fallot constituting 40.5% of all lesions and conotruncal defects, 55.6%. These frequencies exceed the incidence of tetralogy of Fallot (10%) and conotruncal defects (20%) among all children with heart defects (P less than 0.003 for both). Review of patients with deletion 8p (n = 13) showed heart defects in 84.6% with 27.3% being conotruncal defects. Among duplication 8q patients (n = 20), 45% had heart defects with conotruncal defects constituting 44%. Neither group differed significantly from expected in its incidence of conotruncal defects. Among patients with mosaic trisomy 8 (n = 47), 12 had heart abnormalities including one conotruncal defect. Among 3 patients with other rec(8) chromosomes, one had a ventricular septal defect. The cause of heart defects in SLV Rec(8) cannot be assigned to either the deletion of 8p or the duplication of 8q. The lack of an association between other chromosome 8 abnormalities and tetralogy of Fallot suggests that genes at the SLV Rec(8) breakpoints or an interaction between genes on both arms of chromosome 8 are important.

Review of radiologic and clinical findings in the recombinant 8 syndrome

The findings, including radiographic findings, in recombinant 8 syndrome, a rare syndrome in patients with an unbalanced partial duplication/partial deletion of chromosome 8, are described. In addition, the carrier status and heritability are discussed.

Deletions in chromosome 2 and fragile sites

We report on 2 patients with de novo deletions of 2q and chromosome constitutions of 46,XY,del(2)(q32.3q33.3) and 46,XX,del(2) (q21q23.2), respectively. Comparisons of breakpoints of interstitial deletions show frequent correspondence to common fragile sites.

Inv(8)(p23q22) and recombinant derivative in a Sicilian family

A family with inv8(p23q22), in which one girl with a derivative chromosome 8 showed the characteristic phenotype, is reported. Our case differs from the 32 known families with inv8(p23q22), being the first of apparently non-Hispanic descent. The anomaly may, however, have its origins in the Spanish domination of Sicily.

Craniosynostosis update 1987

Information on craniosynostosis in this paper updates "Craniosynostosis: Diagnosis, Evaluation, and Management" (Cohen MM Jr: New York: Raven Press, 1986). It also discusses recent developments that were included in the book but need further explanation or emphasis. Subjects discussed are: epidemiology, etiology, sutural biology, growth and development, neurological and psychosocial aspects, surgery, cloverleaf skulls, craniosynostosis syndromes, and prenatal diagnosis. Under the subject of etiology, fetal head constraint, maternal thyroid disease, calcified cephalohematoma, teratogens, and delayed suture closure and Wormian bones are considered. An updating of 15 cloverleaf skull conditions includes four monogenic disorders, two chromosomal disorders, one disruption, one iatrogenic condition, and seven syndromes of unknown cause. Newly recognized disorders with cloverleaf skull include Beare-Stevenson cutis gyratum syndrome and Say-Poznanski syndrome. Craniosynostosis syndromes and associations discussed include acrocraniofacial dysostosis, Apert syndrome, Beare-Stevenson cutis gyratum syndrome, Calabro syndrome, calvarial hyperostosis, chromosomal craniostenosis, Cole-Carpenter type osteogenesis imperfecta, Crouzon syndrome, Curry-Jones syndrome, Curry variant of Carpenter syndrome, cutis aplasia and cranial stenosis, Fontaine-Farriaux syndrome, Gomex-López-Hernández syndrome, Hersh syndrome, hyper-IgE syndrome and craniostenosis, hypomandibular faciocranial dysostosis, Marfanoid features and craniostenosis, Pfeiffer-type cardiocranial syndrome, Pfeiffer-type dolichocephalosyndactyly, and Say-Barber syndrome.

Partial duplication 8q12----q21.2 in two sibs with maternally derived insertional and reciprocal translocations: case reports and review of partial duplications of chromosome 8

We report on two sibs with duplication of the segment 8q12----8q21.2 resulting from malsegregation of a maternal insertional translocation: [inv ins (5;8)(p13;q12q21.2)]. The mother also carries a reciprocal translocation [t(1;6)(q31;q5)], which was transmitted in the balanced state to the propositi and to a phenotypically normal son and daughter. The literature on two translocations occurring in one individual and on insertional rearrangements is reviewed in terms of reproductive risks to balanced carriers. The two affected infants have a previously undescribed partial duplication of an interstitial segment of 8q and a pattern of abnormalities distinct from those seen in other partial duplications of 8. These infants are reviewed with 78 other cases of partial duplications of chromosome 8 with regard to phenotype-karyotype correlations.

A child with a recombinant of chromosome 8 inherited from her carrier mother

A female child with mental retardation and dysmorphic features was found to have a duplication deficiency of chromosome 8: rec(8)dup q,inv(8)(p23q24), a recombinant product derived from a familial pericentric inversion, inv(8)(p23q24)mat. Clinical features of this previously undescribed inversion product are compared with other reported cases of partial trisomy for the distal long arm of chromosome 8, since this segment is thought to be primarily responsible for the phenotypic features of the trisomy 8 syndrome.

Clinicopathologic and dysmorphic findings in recombinant chromosome 8 syndrome

Clinical records, autopsy reports, and microscopic slides from 11 infants with the recombinant 8 syndrome, an inherited abnormality of chromosome 8 affecting Hispanics from New Mexico and Colorado, were evaluated. A prevalence of cardiac and genitourinary anomalies was found, while few central nervous system abnormalities were observed. Dysmorphic features associated with recombinant 8 syndrome are presented, with descriptions of the inheritance pattern and recurrence risk. Because recombinant 8 syndrome is a chromosomal disorder that will appear more and more frequently as kindreds enlarge, pathologists must be alert to its diagnostic characteristics and genetic implications.

Pericentric inversions. Problems and significance for clinical genetics

A review is given of the incidence, cytogenetics, and biologic relevance of pericentric inversions (pii). In 251 cases in the literature and our patients, 96 different inversion forms with different breakpoints are found. Eighteen of these cases have been observed several times in unrelated families; they are classified as types. The problem of pii in the heterochromatic regions of chromosomes 1 and 9 is especially emphasized and the investigations required are pointed out. The significance of the individual pii is checked with regard to their behavior in meiosis and their phenotypical relevance. An approximately 1:1 segregation is found. Fertility, stillbirth, and rates of abortion are not statistically altered. The gonadal findings available at present in man are reported and commented on. The occurrence of aneusomic recombinants among the live offspring of carriers shows a marked dependence on the length of the relative inversion segments. Since these are distinctly below average in inversion types, they only result in recombinants in exceptional cases. Certain pointers to an above-random common occurrence of other chromosomal aberrations are not found in families with pii. A correlation between pii and clinical symptoms likewise cannot be detected. However, in this connection it is pointed out that trisomic mosaics were observed jointly with pii(9) and pii(22). The review is completed by a brief examination of the literature concerning the significance of pii in evolution.