Small structural changes of chromosome 8. Two cases with evidence for deletion

Shedding light on myopia by studying complete congenital stationary night blindness

Myopia is the most common eye disorder, caused by heterogeneous genetic and environmental factors. Rare progressive and stationary inherited retinal disorders are often associated with high myopia. Genes implicated in myopia encode proteins involved in a variety of biological processes including eye morphogenesis, extracellular matrix organization, visual perception, circadian rhythms, and retinal signaling. Differentially expressed genes (DEGs) identified in animal models mimicking myopia are helpful in suggesting candidate genes implicated in human myopia. Complete congenital stationary night blindness (cCSNB) in humans and animal models represents an ON-bipolar cell signal transmission defect and is also associated with high myopia. Thus, it represents also an interesting model to identify myopia-related genes, as well as disease mechanisms. While the origin of night blindness is molecularly well established, further research is needed to elucidate the mechanisms of myopia development in subjects with cCSNB. Using whole transcriptome analysis on three different mouse models of cCSNB (in Gpr179^-/-, Lrit3^-/- and Grm6^-/-), we identified novel actors of the retinal signaling cascade, which are also novel candidate genes for myopia. Meta-analysis of our transcriptomic data with published transcriptomic databases and genome-wide association studies from myopia cases led us to propose new biological/cellular processes/mechanisms potentially at the origin of myopia in cCSNB subjects. The results provide a foundation to guide the development of pharmacological myopia therapies.

An 8.35 Mb overlapping interstitial deletion of 8q24 in two patients with coloboma, congenital heart defect, limb abnormalities, psychomotor retardation and convulsions

Chromosome analysis in two young patients with multiple congenital anomalies revealed a de novo interstitial deletion of 8q that has not been reported before. The deletions were overlapping by 8.35 Mb (8q24.21q24.23). The clinical features shared by our patients were coloboma, VSD, digital abnormalities, congenital dislocation of a hip, feeding problems, psychomotor delay and convulsions. The deletion included the region for Langer-Giedion syndrome (TRPS1 and EXT1) in the girl only. However, she is too young to present features of this syndrome, apart from dysmorphic features like a bulbous nose and notched alae nasi. Several genes are present in the commonly deleted region, including genes with unknown function, and genes for which haploinsufficiency is known to have no phenotypic effect in mice (Wnt1). A gene that might play a role in the convulsions of our patients is KCNQ3.

A novel 8 Mb interstitial deletion of chromosome 8p12-p21.2

We report on a girl with delayed mental and motor development, ophthalmological abnormalities, and peripheral neuropathy. Chromosome analysis suggested a deletion within chromosome 8p. Further investigation by array-based comparative genomic hybridization (array-CGH) delineated an 8 Mb interstitial deletion on the short arm of chromosome 8. The breakpoints are located at chromosome bands 8p12 and 8p21.2. Forty-two known genes including gonadotropin-releasing hormone 1 (GNRH1), transcription factor EBF2, exostosin-like 3 (EXTL3), glutathione reductase (GSR), and neuregulin 1 (NRG1), are located within the deleted region on chromosome 8p. A comparison of our patient with the cases described in the literature is presented, and we discuss the genotype-phenotype correlation in our patient. This is the first report of array-CGH analysis of an interstitial deletion at chromosome 8p.

Clinical and molecular characterization of two patients with a 6.75 Mb overlapping deletion in 8p12p21 with two candidate loci for congenital heart defects

Clinical and molecular characteristics of two patients with a 6.75Mb overlapping interstitial deletion in the 8p12p21 region are described and compared with previously reported cases with an overlapping deletion. The most common characteristics of interstitial deletions of proximal 8p are developmental delay, postnatal microcephaly and growth retardation. Other frequently reported findings are hypogonadism associated with haploinsufficiency of GNRH1 and ocular problems. Congenital heart anomalies are also common and might at least to some extent be due to haploinsufficiency of NKX2-6 or NRG1. The aforementioned clinical characteristics should be considered in the care of patients with a proximal interstitial 8p12p21 deletion.

A case of primary amenorrhea, diabetes and anosmia

This case details a patient with primary amenorrhea with an unusual cause. She presented at age 16 with short stature, minimal sexual development and no prior menses. Her history was significant for poorly controlled type 1 diabetes. She had been evaluated previously for growth hormone deficiency, and had received a short course of growth hormone therapy. Of greatest significance was the fact that she had also had a decreased sense of smell since her youth. Although a previous computerized tomography scan had been reported as normal, follow-up magnetic resonance imaging demonstrated the absence of olfactory bulbs. Smell testing confirmed the absence of smell and testing of gonadotropin releasing hormone demonstrated an inadequate response. All of these features suggested Kallmann syndrome. This syndrome commonly presents with delayed onset of puberty and decreased or absent sense of smell. There are also many associated features, and the disease is remarkable for its great genotypic and phenotypic variability. Current understanding of its pathogenesis, the commonly associated features of Kallmann syndrome and the impact of diabetes on growth and sexual development are reviewed.

Human fertilin beta: identification, characterization, and chromosomal mapping of an ADAM gene family member

Fertilin alpha/beta (PH30 alpha/beta) is a heterodimeric sperm surface protein containing binding and fusion domains with potential for interaction with integrin receptors on the oocyte. We report the cDNA cloning, deduced amino acid sequence, tissue specificity, and chromosomal mapping of human fertilin beta. Encoded by a 2205 nucleotide open reading frame, the deduced amino acid sequence of human fertilin beta contains pro-, metalloprotease-like, disintegrin-like, cysteine-rich, epidermal growth factor-like (EGF) repeat, transmembrane, and cytoplasmic domains. Due to this domain organization, human fertilin beta has been identified as a member of the ADAM family, which is composed of membrane-anchored proteins having A Disintegrin And Metalloprotease domain. The amino acid sequence of human fertilin beta shares 90%, 56%, and 55% identity, respectively, to monkey, guinea pig, and mouse fertilin beta homologs. A phenylalanine-glutamate-glutamate (FEE) binding tripeptide within the disintegrin-like domain of human fertilin beta, homologous to other fertilin beta RGD-like (arginine-glycine-aspartic acid) tripeptides, could compete for recognition by integrins and other receptors. Northern analysis from 16 human tissues revealed human fertilin beta's 2.9 kb message only in testis, which raises interest in possible clinical applications of this molecule as a contraceptive vaccinogen. Human fertilin beta maps to chromosome 8, band p11.2, by fluorescence in situ hybridization and mouse/human somatic cell hybrid Southern hybridization.

Distal 8p deletion (8)(p23.1): an easily missed chromosomal abnormality that may be associated with congenital heart defect and mental retardation

We describe the clinical manifestations and molecular cytogenetic analyses of three patients with a similar distal deletion of chromosome 8. Each child had mild developmental delay and subtle minor anomalies. Two had cardiac anomalies but no other major congenital anomalies were present. High resolution G and R banding showed in all three patients del(8)(p23.1), but the breakpoint in case 1 was distal to 8p23.1, in case 2 was in the middle of 8p23.1, and in case 3 proximal to 8p23.1. Fluorescence in situ hybridization (FISH) studies with a chromosome 8 paint probe confirmed that no other rearrangement had occurred. FISH with a chromosome 8-specific telomere probe indicated that two patients had terminal deletions. Chromosome analysis of the parents of case 1 and mother of case 2 were normal; the remaining parents were not available for study. Thirteen individual patients including the three in this study, and three relatives in one family with del(8)(p23.1), have been reported in the past 5 years. Major congenital anomalies, especially congenital heart defects, are most often associated with a breakpoint proximal to 8p23.1. Three patients were found within a 3-year period in this study and five cases were found within 4 years by another group, indicating that distal 8p deletion might be a relatively common chromosomal abnormality. This small deletion is easily overlooked (i.e., cases 1 and 2 were reported as normal at amniocentesis) and can be associated with few or no major congenital anomalies.

Interstitial deletion of 8p: report of two patients and review of the literature

Two female infants with de novo interstitial deletions of 8p were studied. One with a deletion from p11.21 to p11.23, and the other patient with a deletion from p11.23 to p21.3 had several clinical manifestations of the terminal 8p- syndrome. Band 8p11.23 was deleted in both patients. The clinical manifestations common to both patients included low birthweight, growth deficiency, congenital heart disease, mental retardation, dolichocephaly, low-set, malformed ears, high-arched palate, thin lips and micrognathia. Since these features may occur in most patients with chromosomal imbalance, and the terminal 8p- syndrome has hitherto been assumed to result from terminal deletions of 8p, ranging from p21.3 to p23, it is likely that these features are simply related to the chromosomal imbalance rather than to band specific imbalance of 8p11.23. The present study suggests that two different types of deletion, interstitial and terminal, are associated with still poorly defined, rather non-specific clinical features.

Pure chromosome-specific PCR libraries from single sorted chromosomes

Chromosome-specific DNA libraries can be very useful in molecular and cytogenetic genome mapping studies. We have developed a rapid and simple method for the generation of chromosome-specific DNA sequences that relies on polymerase chain reaction (PCR) amplification of a single flow-sorted chromosome or chromosome fragment. Previously reported methods for the development of chromosome libraries require larger numbers of chromosomes, with preparation of pure chromosomes sorted by flow cytometry, generation of somatic cell hybrids containing targeted chromosomes, or a combination of both procedures. These procedures are labor intensive, especially when hybrid cell lines are not already available, and this has limited the generation of chromosome-specific DNA libraries from nonhuman species. In contrast, a single sorted chromosome is a pure source of DNA for library production even when flow cytometric resolution of chromosome populations is poor. Furthermore, any sorting cytometer may be used with this technique. Using this approach, we demonstrate the generation of PCR libraries suitable for both molecular and fluorescence in situ hybridization studies from individual baboon and canine chromosomes, separate human homologues, and a rearranged marker chromosome from a transformed cell line. PCR libraries specific to subchromosomal regions have also been produced by sorting a small chromosome fragment. This simple and rapid technique will allow generation of nonhuman linkage maps and probes for fluorescence in situ hybridization and the characterization of marker chromosomes from solid tumors. In addition, allele-specific libraries generated by this strategy may also be useful for mapping genetic diseases.

Interstitial deletion 8p21.3----p23.1 in a 6-year-old girl

We present a 6-year-old mentally retarded girl. Chromosome analysis showed an interstitial deletion of chromosome 8; 46,XX,del(8) (pter----p23.1::p21.3----qter). The proposita had normal activities of glutathione synthetase reductase (GSR) and factor VII. Parental chromosomes were normal.

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.

Partial monosomy 8p with minimal dysmorphic signs

A female patient with a 46,XX,del(8)(p23----pter) karyotype is presented. She was mentally retarded and showed a few dysmorphic features. Her red cell glutathione reductase level was within normal limits. This terminal deletion, on the short arm of chromosome 8, appears to be the smallest segment hitherto reported.

Deficiency of distal 8p--report of two cases and review of the literature

A terminal deletion in the short arm of chromosome 8 was found in a 2.5-year-old boy: 46,XY,del(8) (p22.0) and in a 1-year-old girl: 46,XX,del(8) (p23.1) with dysmorphic craniofacial features and developmental retardation. Erythrocyte GSR activities of the boy and of his parents were within normal limits. Vitamin K dependent coagulation factors in the girl and her parents gave normal results. Clinical findings were compared with previously reported cases and suggested a recognizable syndrome.

Tricho-rhino-phalangeal and branchio-oto syndromes in a family with an inherited rearrangement of chromosome 8q

Here we report on a family with an inherited rearrangement of chromosome 8q, dir ins(8)(q24.11q13.3q21.13). Individuals with the chromosome abnormality, which does not appear to be associated with deletion of chromosome material, have manifestations of both tricho-rhino-phalangeal syndrome (TRPS) and branchio-oto syndrome (BOS). TRPS has been linked previously to deletions involving 8q24.11----q24.13, but none of the described patients with deletions in this part of 8q have had characteristics of the BOS. The presence of a breakpoint in 8q24.11 without apparent chromosome deletion in the family described suggests that TRPS maps to this band of 8q. Further, it is suggested that BOS maps to either 8q13.3 or 8q21.13.

Partial deletion 8q without Langer-Giedion syndrome: a recognisable syndrome

We report two de novo cases of del(8)(pter----q24.1:) with breakpoints involving the distal part of band 8q24.1. The clinical features were similar and there were no obvious stigmata of Langer-Giedion syndrome (LGS). There are three other cases reported with a deletion of chromosome 8 at approximately the same breakpoint, one without LGS and some similarities to our cases, the other two with LGS. Our findings would support the observation that the critical segment for the assignment of LGS is proximal to or involves the proximal part of 8q24.1, but a review of published reports suggests that the aetiology of LGS may be a more complex issue.

Localization of the spherocytosis gene to chromosome segment 8p11.22----8p21

A case of hereditary spherocytosis (HS) is reported. Cytogenetic study revealed a de novo minute deletion of chromosome 8. The critical portion which affected the expression of the HS phenotype appeared to be localized to 8p11.22----8p21.1.

Interstitial deletion of the long arm of chromosome 8 without Langer-Giedion syndrome

A case of interstitial deletion of the long arm of chromosome 8 is reported. A chromosome analysis by a high resolution banding revealed the abnormal karyotype, 46, XY, del (8) (q11.2q13). Although some reports describe an association of 8q deletion with the Langer-Giedion syndrome, this patient did not have the typical features of this syndrome. It was noted that the patient had amino aciduria, EEG and ECG abnormalities together with other pathological findings.

Monosomy 8p: an easily overlooked syndrome

Two patients with partial monosomy of the short arm of chromosome 8 are described. Their clinical features were very similar. Comparison with previously reported patients confirms the existence of an 8p- syndrome. The importance of cytogenetic investigations in all infants with major congenital heart defect and facial dysmorphism or microcephaly or both is stressed.

Deficiency of chromosome 8p21.1----8pter: case report and review of the literature

The clinical manifestations and cytogenetic changes of a patient with 46,XY,del(8)(p21.1) are compared with those of nine other patients with a similar deficiency of chromosome 8. Patients with this chromosome anomaly have a syndrome of postnatal growth retardation, microcephaly, mental retardation, epicanthal folds, posteriorly angulated and malformed ears, short neck, relatively increased internipple distance, and congenital heart defect. A short and broad nose, a wide and flat nasal bridge, and a small jaw are observed in young patients but tend to become less apparent with increasing age. In most instances, the syndrome has been associated with a de novo chromosome abnormality. Levels of glutathione reductase in our patient were normal-a finding consistent with localization of the gene coding for this enzyme to the proximal part of band 8p21.1 if gene dosage studies are reliable.

Complex translocation in a boy with trichorhinophalangeal syndrome

We report a boy with a trichorhinophalangeal syndrome (TRP syndrome), severe mental retardation, and transient megacephaly, whose karyotype showed complex, apparently balanced, translocations with breakpoints in bands 3q13, 8p22, 8q13, 11p12, and 11q21. The fact that cases presenting with phenotypes corresponding to the TRP II syndrome and deletions of the long arm of chromosome 8 have been recently reported prompted us to report this case to help in the clarification of the possible relation between 8q chromosomal mutation and the aetiology of TRP syndromes.

Unbalanced karyotype with normal phenotype in a family with translocation (8;13)(p21;q22)

We describe a family with translocation (8;13) (p21;q22), in which both unbalanced products of adjacent-1 segregation occurred. Two members of the family have partial trisomy 8p with partial monosomy 13q; two others have partial monosomy 8p with partial trisomy 13q. The latter are both phenotypically normal, which is a highly unusual observation. One of these is, in addition, a carrier of a de novo balanced translocation between chromosomes 2 and 19. The risk for unbalanced progeny is discussed.

Chromosomal abnormalities associated with congenital contractures (arthrogryposis)

In a study of 350 patients with multiple congenital contractures (arthrogryposis), 80 (23%) patients had mental retardation or were developmentally delayed. Out of that group of 80 patients, 13 (16%) were found to have abnormal karyotypes. Two of the thirteen had a family history of chromosomal abnormalities without congenital contractures, therefore, 11 patients had chromosomal anomalies which appeared to be associated with the congenital contractures. Five of the eleven (45%) had chromosome mosaicism, three of those had tissue mosaicism. Two had abnormal skin fibroblast cell lines and normal peripheral leukocyte chromosome studies and one had a normal bone marrow karyotype with abnormal peripheral leukocyte chromosome studies. Chromosome studies were done in these patients with congenital contractures because of developmental delay and multisystem involvement, or recognition of clinical features typical of a chromosomal syndrome. We recommend first lymphocyte; and if those are normal, then fibroblast studies be done on all patients with multiple joint contractures and developmental delay, particularly if unusual facial features or multisystem abnormalities are present.

A complex rearrangement, including a deleted 8q, in a case of Langer-Giedion syndrome

A 10-month-old infant with failure to thrive, delayed development, mild dysmorphia, cardiac anomalies, and cryptorchidism was referred for cytogenetic evaluation. Routine GTG-banded analysis revealed a modal number of 46 chromosomes, which contained an obvious complex rearrangement involving chromosomes 1, 8, and 14. Parental chromosomes were normal. Following high resolution techniques, this de novo rearrangement demonstrated an intraband deletion and was designated as [46,XY,t(1;8;14)(1pter----1p13.1::14q12----14pter++ +;1qter----1p13.1::8q24.13----8qter; 14qter----14q12::8p23.3----8q24.11:)]. Although deletions have been implicated as possibly responsible for abnormal phenotypes in patients with de novo "balanced rearrangements", in most cases, they could not be demonstrated. The present case is only the second instance documenting a subtle intraband deletion in association with a complex translocation. Fourteen of the reported 18 patients with an 8q deletion (including this infant) have Langer-Giedion syndrome, suggesting an etiologic relationship. However, the same deletion is not present in all cases.

The tricho-rhino-phalangeal syndrome with exostoses (or Langer-Giedion syndrome): four additional patients without mental retardation and review of the literature

We report on four patients with tricho-rhino-phalangeal syndrome with exostoses (TRPSE) who were not mentally retarded and review 32 previously published cases. These data enable more complete delineation of the phenotype and document the variability of the clinical and radiographic manifestations. Information on the genetics and the association with del(8q) is discussed, as are management and avenues for further investigation. The apparent variability of intelligence in TRPSE patients together with the high incidence of other problems, including significant delay in speech development and hearing loss, make systematic multidisciplinary evaluation and long-term treatment necessary to achieve the best outcome.

Terminal or interstitial deletion in chromosome 8 long arm in Langer-Giedion syndrome (TRP II syndrome)?

Reexamination with high resolution banding of the first ever published case of Langer-Giedion syndrome with 8q deletion as well as chromosome examination of a second case of this syndrome with different high resolution methods, confirmed our previous assumption of a terminal 8q involvement in the causation of TRP II syndrome.

Two cases of the Langer-Giedion syndrome with the same interstitial deletion of the long arm of chromosome 8: 46, XY or XX, del (8) (q23.3q24.13)

Two cases of the Langer-Giedion syndrome (LGS) are reported. Chromosome analysis by high-resolution banding with 850 bands revealed the same abnormal karyotype, 46,XY or XX,del(8)(q23.3q24.13), which was the smallest deletion among those of LGS patients with 8q deletion. The deleted segments found in three patients with LGS analyzed by high-resolution banding have a part of 8q23.3 and 8q24.11 in common.

Langer-Giedion syndrome, in a child with complex structural aberration of chromosome 8

A patient with typical features of the Langer-Giedion syndrome (tricho-rhino-phalangeal syndrome, type II) is described. In the karyotype an interstitial deletion of the long arm of chromosome 8 (band 8q22) was observed as the result of a complex rearrangement of chromosomes 1 and 8: 46,XY inv(8)(q23 leads to q242), del(8)(q221 leads to q223), ins(8;1) (q221;p321 p341;q242). Previously reported cases of Langer-Giedion syndrome with deletion of 8q are compared with the present one.

Familial inversion translocation (8;13) with partial trisomy 13 in several family members

A partial trisomy 13q was observed in siblings with hexadactylia, hypertelorism, hemangioma and severe psychomotor retardation. It originated from a maternal inversion translocation 46,XX,inv(8)(q23q241),t(8;13)(q241;q32). The family showed a pedigree pattern typical for the segregation of a chromosomal translocation. In spite of this the diagnosis was delayed several years, because the bands involved from the two chromosomes were of great similarity. This stresses the importance of reinvestigating families with a clinical suspicion of a chromosomal syndrome, preferentially with prometaphase chromosomes. The identification of a chromosomal rearrangement is essential for genetic counselling and prenatal diagnosis.

Langer-Giedion syndrome and additional congenital malformations with interstitial deletion of the long arm of chromosome 8 46, XY, del 8 (q 13-22)

Deletion of the long arm of chromosome 8 was found in a mentally retarded boy with typical features of the Langer-Giedion syndrome (TRP syndrome type II). Additional malformations were colobomata of the iris and partial syndactyly of the 4th and 5th fingers.

Presumptive long arm deletion of chromosome 8: a new syndrome?

This communication describes an infant with growth and psychomotor retardation and severe congenital malformations, who was found to have an interstitial deletion of the long arm of chromosome 8: 46,XY,del(8) (q13q22). Comparison with the only other previously reported patient with a deletion of a similar chromosomal segment suggested that deletion of the long arm of chromosome 8 may constitute a clinically recognizable syndrome.

Interstitial deletion of the long arm of chromosome 8. Karyotype: 46,XY,del(8)(q21)

This report describes a polymalformed 18-month-old male with an interstitial deletion of the long arm of chromosome 8. His karyotype is: 46,XY,del(8)(q21).

The 8p- syndrome

A boy with severe retardation of growth and development, minor dysmorphic features, severe congenital heart disease, and a 46,XY,8p-karyotype is described. The clinical findings of this boy are compared with those of others reported monosomic for a portion of the short arm of chromosome 8. The red cell glutathione reductase (GSR) level is normal in our patient.