4
|
South ST, Whitby H, Battaglia A, Carey JC, Brothman AR. Comprehensive analysis of Wolf–Hirschhorn syndrome using array CGH indicates a high prevalence of translocations. Eur J Hum Genet 2007; 16:45-52. [PMID: 17726485 DOI: 10.1038/sj.ejhg.5201915] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Wolf-Hirschhorn syndrome (WHS) is caused by deletions involving chromosome region 4p16.3. The minimal diagnostic criteria include mild-to-severe mental retardation, hypotonia, growth delay and a distinctive facial appearance. Variable manifestations include feeding difficulties, seizures and major congenital anomalies. Clinical variation may be explained by variation in the size of the deletion. However, in addition to having a deletion involving 4p16.3, previous studies indicate that approximately 15% of WHS patients are also duplicated for another chromosome region due to an unbalanced translocation. It is likely that the prevalence of unbalanced translocations resulting in WHS is underestimated since they can be missed using conventional chromosome analyses such as karyotyping and WHS-specific fluorescence in situ hybridization (FISH). Therefore, we hypothesized that some of the clinical variation may be due to an unrecognized and unbalanced translocation. Array comparative genomic hybridization (aCGH) is a new technology that can analyze the entire genome at a significantly higher resolution over conventional cytogenetics to characterize unbalanced rearrangements. We used aCGH to analyze 33 patients with WHS and found a much higher than expected frequency of unbalanced translocations (15/33, 45%). Seven of these 15 cases were cryptic translocations not detected by a previous karyotype combined with WHS-specific FISH. Three of these 15 cases had an unbalanced translocation involving the short arm of an acrocentric chromosome and were not detected by either aCGH or subtelomere FISH. Analysis of clinical manifestations of each patient also revealed that patients with an unbalanced translocation often presented with exceptions to some expected phenotypes.
Collapse
Affiliation(s)
- Sarah T South
- Division of Medical Genetics, Department of Pediatrics, University of Utah, Salt Lake City, UT, USA.
| | | | | | | | | |
Collapse
|
5
|
South ST, Bleyl SB, Carey JC. Two unique patients with novel microdeletions in 4p16.3 that exclude the WHS critical regions: Implications for critical region designation. Am J Med Genet A 2007; 143A:2137-42. [PMID: 17696124 DOI: 10.1002/ajmg.a.31900] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Wolf-Hirschhorn syndrome (WHS) is characterized by growth delay, developmental delay, hypotonia, seizures, feeding difficulties, and characteristic facial features. Deletion of either of two critical regions (WHSCR and WHSCR-2) within chromosome band 4p16.3 has been proposed as necessary for the minimal clinical manifestations of WHS and controversy remains regarding their designation. We describe two patients with novel terminal microdeletions in 4p16.3 who lack the characteristic facial features but do show some of the more nonspecific manifestations of WHS. The first patient had a ring chromosome 4 with an intact 4q subtelomere and a terminal 4p microdeletion of approximately 1.27-1.46 Mb. This deletion was distal to both proposed critical regions. The second patient had a normal karyotype with a terminal 4p microdeletion of approximately 1.78 Mb. This deletion was distal to WHSCR and the breakpoint was near or within the known distal boundary for WHSCR-2. Both patients showed significant postnatal growth delay, mild developmental delays and feeding difficulties. Their facial features were not typical for WHS. The phenotype of the first patient may have been influenced by the presence of a ring chromosome. Seizures were absent in the first patient whereas the second patient had a complex seizure disorder. Characterization of these patients supports the hypothesis that a gene in WHSCR-2, LETM1, plays a direct role in seizure development, and demonstrates that components of the WHS phenotype can be seen with deletions distal to the known boundaries of the two proposed critical regions. These patients also emphasize the difficulty of mapping clinical manifestations common to many aneusomy syndromes.
Collapse
Affiliation(s)
- Sarah T South
- Department of Pediatrics, Division of Medical Genetics, University of Utah, Salt Lake City, Utah 84132-2117, USA.
| | | | | |
Collapse
|
7
|
Holinski-Feder E, Reyniers E, Uhrig S, Golla A, Wauters J, Kroisel P, Bossuyt P, Rost I, Jedele K, Zierler H, Schwab S, Wildenauer D, Speicher MR, Willems PJ, Meitinger T, Kooy RF. Familial mental retardation syndrome ATR-16 due to an inherited cryptic subtelomeric translocation, t(3;16)(q29;p13.3). Am J Hum Genet 2000; 66:16-25. [PMID: 10631133 PMCID: PMC1288322 DOI: 10.1086/302703] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/1999] [Accepted: 10/06/1999] [Indexed: 11/03/2022] Open
Abstract
In the search for genetic causes of mental retardation, we have studied a five-generation family that includes 10 individuals in generations IV and V who are affected with mild-to-moderate mental retardation and mild, nonspecific dysmorphic features. The disease is inherited in a seemingly autosomal dominant fashion with reduced penetrance. The pedigree is unusual because of (1) its size and (2) the fact that individuals with the disease appear only in the last two generations, which is suggestive of anticipation. Standard clinical and laboratory screening protocols and extended cytogenetic analysis, including the use of high-resolution karyotyping and multiplex FISH (M-FISH), could not reveal the cause of the mental retardation. Therefore, a whole-genome scan was performed, by linkage analysis, with microsatellite markers. The phenotype was linked to chromosome 16p13.3, and, unexpectedly, a deletion of a part of 16pter was demonstrated in patients, similar to the deletion observed in patients with ATR-16 syndrome. Subsequent FISH analysis demonstrated that patients inherited a duplication of terminal 3q in addition to the deletion of 16p. FISH analysis of obligate carriers revealed that a balanced translocation between the terminal parts of 16p and 3q segregated in this family. This case reinforces the role of cryptic (cytogenetically invisible) subtelomeric translocations in mental retardation, which is estimated by others to be implicated in 5%-10% of cases.
Collapse
Affiliation(s)
- Elke Holinski-Feder
- Departments of Medical Genetics and Human Genetics, University of Munich, Munich; Department of Medical Genetics, University of Antwerp, Antwerp; Department of Human Genetics, University of Graz, Graz, Austria; and Department of Human Genetics, University of Bonn, Bonn
| | - Edwin Reyniers
- Departments of Medical Genetics and Human Genetics, University of Munich, Munich; Department of Medical Genetics, University of Antwerp, Antwerp; Department of Human Genetics, University of Graz, Graz, Austria; and Department of Human Genetics, University of Bonn, Bonn
| | - Sabine Uhrig
- Departments of Medical Genetics and Human Genetics, University of Munich, Munich; Department of Medical Genetics, University of Antwerp, Antwerp; Department of Human Genetics, University of Graz, Graz, Austria; and Department of Human Genetics, University of Bonn, Bonn
| | - Astrid Golla
- Departments of Medical Genetics and Human Genetics, University of Munich, Munich; Department of Medical Genetics, University of Antwerp, Antwerp; Department of Human Genetics, University of Graz, Graz, Austria; and Department of Human Genetics, University of Bonn, Bonn
| | - Jan Wauters
- Departments of Medical Genetics and Human Genetics, University of Munich, Munich; Department of Medical Genetics, University of Antwerp, Antwerp; Department of Human Genetics, University of Graz, Graz, Austria; and Department of Human Genetics, University of Bonn, Bonn
| | - Peter Kroisel
- Departments of Medical Genetics and Human Genetics, University of Munich, Munich; Department of Medical Genetics, University of Antwerp, Antwerp; Department of Human Genetics, University of Graz, Graz, Austria; and Department of Human Genetics, University of Bonn, Bonn
| | - Paul Bossuyt
- Departments of Medical Genetics and Human Genetics, University of Munich, Munich; Department of Medical Genetics, University of Antwerp, Antwerp; Department of Human Genetics, University of Graz, Graz, Austria; and Department of Human Genetics, University of Bonn, Bonn
| | - Imma Rost
- Departments of Medical Genetics and Human Genetics, University of Munich, Munich; Department of Medical Genetics, University of Antwerp, Antwerp; Department of Human Genetics, University of Graz, Graz, Austria; and Department of Human Genetics, University of Bonn, Bonn
| | - Kerry Jedele
- Departments of Medical Genetics and Human Genetics, University of Munich, Munich; Department of Medical Genetics, University of Antwerp, Antwerp; Department of Human Genetics, University of Graz, Graz, Austria; and Department of Human Genetics, University of Bonn, Bonn
| | - Hannelore Zierler
- Departments of Medical Genetics and Human Genetics, University of Munich, Munich; Department of Medical Genetics, University of Antwerp, Antwerp; Department of Human Genetics, University of Graz, Graz, Austria; and Department of Human Genetics, University of Bonn, Bonn
| | - Sieglinde Schwab
- Departments of Medical Genetics and Human Genetics, University of Munich, Munich; Department of Medical Genetics, University of Antwerp, Antwerp; Department of Human Genetics, University of Graz, Graz, Austria; and Department of Human Genetics, University of Bonn, Bonn
| | - Dieter Wildenauer
- Departments of Medical Genetics and Human Genetics, University of Munich, Munich; Department of Medical Genetics, University of Antwerp, Antwerp; Department of Human Genetics, University of Graz, Graz, Austria; and Department of Human Genetics, University of Bonn, Bonn
| | - Michael R. Speicher
- Departments of Medical Genetics and Human Genetics, University of Munich, Munich; Department of Medical Genetics, University of Antwerp, Antwerp; Department of Human Genetics, University of Graz, Graz, Austria; and Department of Human Genetics, University of Bonn, Bonn
| | - Patrick J. Willems
- Departments of Medical Genetics and Human Genetics, University of Munich, Munich; Department of Medical Genetics, University of Antwerp, Antwerp; Department of Human Genetics, University of Graz, Graz, Austria; and Department of Human Genetics, University of Bonn, Bonn
| | - Thomas Meitinger
- Departments of Medical Genetics and Human Genetics, University of Munich, Munich; Department of Medical Genetics, University of Antwerp, Antwerp; Department of Human Genetics, University of Graz, Graz, Austria; and Department of Human Genetics, University of Bonn, Bonn
| | - R. Frank Kooy
- Departments of Medical Genetics and Human Genetics, University of Munich, Munich; Department of Medical Genetics, University of Antwerp, Antwerp; Department of Human Genetics, University of Graz, Graz, Austria; and Department of Human Genetics, University of Bonn, Bonn
| |
Collapse
|
8
|
Knight SJ, Regan R, Nicod A, Horsley SW, Kearney L, Homfray T, Winter RM, Bolton P, Flint J. Subtle chromosomal rearrangements in children with unexplained mental retardation. Lancet 1999; 354:1676-81. [PMID: 10568569 DOI: 10.1016/s0140-6736(99)03070-6] [Citation(s) in RCA: 341] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
BACKGROUND No explanation for moderate to severe mental retardation is apparent in about 40% of cases. Although small chromosomal rearrangements may account for some undiagnosed cases, a lack of genome-wide screening methods has made it impossible to ascertain the frequency of such abnormalities. METHODS A fluorescence in-situ hybridisation (FISH) test was used to examine the integrity of chromosome ends in 284 children with unexplained moderate to severe retardation, and in 182 children with unexplained mild retardation. 75 normal men were also tested. When a chromosomal rearrangement was found, its size was estimated, and members of the child's family were investigated. FINDINGS Subtle chromosomal abnormalities occurred with a frequency of 7.4% in the children with moderate to severe mental retardation, and of 0.5% in the children with mild retardation. The abnormalities had an estimated population prevalence of 2.1 per 10,000, and were familial in almost half of cases. INTERPRETATION Once recognisable syndromes have been excluded, abnormalities that include the ends of chromosomes are the commonest cause of mental retardation in children with undiagnosed moderate to severe mental retardation. Owing to the high prevalence of familial cases, screening for subtle chromosomal rearrangements is warranted in children with unexplained moderate to severe mental retardation.
Collapse
Affiliation(s)
- S J Knight
- Institute of Molecular Medicine, John Radcliffe Hospital, Oxford, UK
| | | | | | | | | | | | | | | | | |
Collapse
|
12
|
Sankaranarayanan K. Ionizing radiation and genetic risks. X. The potential "disease phenotypes" of radiation-induced genetic damage in humans: perspectives from human molecular biology and radiation genetics. Mutat Res 1999; 429:45-83. [PMID: 10434024 DOI: 10.1016/s0027-5107(99)00100-1] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Estimates of genetic risks of radiation exposure of humans are traditionally expressed as expected increases in the frequencies of genetic diseases (single-gene, chromosomal and multifactorial) over and above those of naturally-occurring ones in the population. An important assumption in expressing risks in this manner is that gonadal radiation exposures can cause an increase in the frequency of mutations and that this would result in an increase in the frequency of genetic diseases under study. However, despite compelling evidence for radiation-induced mutations in experimental systems, no increases in the frequencies of genetic diseases of concern or other adverse effects (i.e., those which are not formally classified as genetic diseases), have been found in human studies involving parents who have sustained radiation exposures. The known differences between spontaneous mutations that underlie naturally-occurring single-gene diseases and radiation-induced mutations studied in experimental systems now permit us to address and resolve these issues to some extent. The fact that spontaneous mutations (among which are point mutations and DNA deletions generally restricted to the gene) originate through a number of different mechanisms and that the latter are intimately related to the DNA organization of the genes, are now well-documented. Further, spontaneous mutations include those that cause diseases through loss of function as well as gain of function of genes. In contrast, most radiation-induced mutations studied in experimental systems (although identified through the phenotypes of the marker genes) are predominantly multigene deletions which cause loss of function; the recoverability of an induced deletion in a livebirth seems dependent on whether the gene and the genomic region in which it is located can tolerate heterozygosity for the deletion and yet be compatible with viability. In retrospect, the successful mutation test systems (such as the mouse specific locus test) used in radiation studies have involved genes which are non-essential for survival and are also located in genomic regions, likewise non-essential for survival. In contrast, most of the human genes at which induced mutations have been looked for, do not seem to have these attributes. The inference therefore is that the failure to find induced germline mutations in humans is not due to the resistance of human genes to induced mutations but due to the structural and functional constraints associated with their recoverability in livebirths. Since the risk of inducible genetic diseases in humans is estimated using rates of "recovered" mutations in mice, there is a need to introduce appropriate correction factors to bridge the gap between these rates and the rates at which mutations causing diseases are potentially recoverable in humans. Since the whole genome is the "target" for radiation-induced genetic damage, the failure to find increases in the frequencies of specific single-gene diseases of societal concern does not imply that there are no genetic risks of radiation exposures: the problem lies in delineating the phenotypes of recoverable genetic damage that are recognizable in livebirths. Data from studies of naturally-occurring microdeletion syndromes in humans and those from mouse radiation studies are instructive in this regard. They (i) support the view that growth retardation, mental retardation and multisystem developmental abnormalities are likely to be among the quantitatively more important adverse effects of radiation-induced genetic damage than mutations in a few selected genes and (ii) underscore the need to expand the focus in risk estimation from known genetic diseases (as has been the case thus far) to include these induced adverse developmental effects although most of these are not formally classified as "genetic diseases". (ABSTRACT TRUNCATED)
Collapse
Affiliation(s)
- K Sankaranarayanan
- MGC, Department of Radiation Genetics and Chemical Mutagenesis, Leiden University Medical Centre, Sylvius Laboratories, Wassenaarseweg 72, 2333 AL, Leiden, Netherlands.
| |
Collapse
|
13
|
Chen CP, Chern SR, Lee CC, Chen WL, Chen MH, Chang KM. De novo unbalanced translocation resulting in monosomy for proximal 14q and distal 4p in a fetus with intrauterine growth retardation, Wolf-Hirschhorn syndrome, hypertrophic cardiomyopathy, and partial hemihypoplasia. J Med Genet 1998; 35:1050-3. [PMID: 9863609 PMCID: PMC1051524 DOI: 10.1136/jmg.35.12.1050] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
We present the perinatal findings of a fetus with a de novo unbalanced chromosome translocation that resulted in monosomy for proximal 14q and monosomy for distal 4p. Prenatal sonographic examination at 27 weeks of gestation showed intrauterine growth retardation, microcephaly, cardiomegaly with arrhythmia, and asymmetry of the upper limbs. Genetic amniocentesis showed an abnormal karyotype of 45,XX,der(4)t(4;14)(p16.3;q12),-14. Linkage analysis of the family confirmed the maternal origin of the deletions. Molecular refinement of the deletion breakpoints indicated that the breakpoints at 4p16.3 and 14q12 were located between loci D4S403 (present) and D4S394 (absent), and between loci D14S252 (present) and D14S64 (absent), respectively. Necropsy showed dysmorphic features compatible with Wolf-Hirschhorn syndrome, hypertrophic cardiomyopathy, partial hemihypoplasia, and a normal brain without evidence of holoprosencephaly. Our case adds to the list of clinical phenotypes associated with the proximal regions of 14q.
Collapse
Affiliation(s)
- C P Chen
- Department of Obstetrics and Gynaecology, Mackay Memorial Hospital, Taipei, Taiwan
| | | | | | | | | | | |
Collapse
|