Molecular characterization of an 11q interstitial deletion in a patient with the clinical features of Jacobsen syndrome

The 11q terminal deletion disorder or Jacobsen syndrome is a contiguous gene disorder. It is characterized by psychomotor retardation, cardiac defects, blood dyscrasias (Paris-Trousseau syndrome) and craniofacial anomalies. We report on a female patient with an approximately 10 Mb interstitial deletion with many of the features of Jacobsen syndrome: A congenital heart defect, dysmorphic features, developmental delay, and Paris-Trousseau syndrome. The karyotype of the patient is 46,XX,del(11)(q24.1q24.3). The interstitial deletion was confirmed using FISH probes for distal 11q, and the breakpoints were characterized by microarray analysis. This is the first molecularly characterized interstitial deletion in a patient with the clinical features of Jacobsen syndrome. The deletion includes FLI-1, but not JAM-3, which will help to determine the critical genes involved in this syndrome.     

Ring-11 chromosome: Phenotype-karyotype correlation with deletions of 11q

The cytogenetic evaluation of a female infant with congenital anomalies led to the identification of the second reported case of a ring-11 chromosome. Unlike the previously described case, in which the patient had only minimal clinical findings and no demonstrable loss of material from the ring, our patient had numerous anomalies that were asssociated with a substantial deficiency of 11q material. The different phenotypes in these two cases represent variation in the amount and location of the chromosomal material lost during the genesis of the ring. The manifestations of this patient and the deletion of region q24→qter from the ring-11 identify a specific chromosome deletion syndrome referred to as del (11q) syndrome.     

Complex cytogenetic rearrangement of chromosome 8q in a case of Ambras syndrome

Ambras syndrome (AMS) is a unique form of congenital universal hypertrichosis. The syndrome has been found in association with rearrangements of chromosome 8 in two isolated cases. One of these patients was reported to have an apparently balanced paracentric inversion of chromosome 8, inv(8)(q12q22). Our cytogenetic analysis on this patient showed that the rearrangement of chromosome 8 is more complex than initially reported. We detected an insertion of the q23-q24 region into a more proximal region of the long arm of chromosome 8 as well as a large deletion in 8q23:46,XX, rea(8)(8pter-->8q13::8q23.2-->8q24.1::8q13-->8q23.1::8q24.1-->8qter). Given the large number of breakpoints and the presence of a substantial deletion, it is surprising that the proposita did not show anomalies other than these characteristic of Ambras syndrome.     

Untreated growth hormone deficiency with extremely short stature, bone dysplasia, cleft lip--palate and severe mental retardation in a 26-year-old man with a de novo unbalanced translocation t(1;12)(q24;q24)

We report on a 26-year-old patient presenting with extremely short stature (height 72 cm, weight 6.5 kg, OFC 42.5 cm), facial dysmorphism, cleft lip–palate, severe mental retardation and de novo 1q24.2–q25.2 and 12q24.31 interstitial deletion. He was the only child of non-consanguineous parents and his birth length was 43 cm. He had severe feeding difficulties and required enteral nutrition until the age of 3 years. Standard cytogenetic analysis showed an apparently balanced de novo translocation t(1;12)(q24;q24). Endocrine studies at 11 years of age for severe growth retardation revealed multiple pituitary hormone deficiency with severe growth hormone deficiency, but the child was untreated because of associated mental retardation. At 26 years of age, he could not walk or speak and had no signs of puberty. Investigations revealed spondylo-epi-metaphyseal dysplasia with severe osteoporosis, enlarged aorta when compared to the patient's size and apparently normal pituitary development. High resolution karyotype showed a 1q24–q25 deletion, and comparative genomic hybridization studies confirmed the 1q interstitial deletion. FISH studies of both breakpoints using PACs and BACs enabled us to further characterize the 1q interstitial deletion (1q24.2–1q25.2) and also revealed a 12q24.31 interstitial microdeletion. This case is compared with previously reported patients with similar deletions, but the untreated pituitary deficiency could also be responsible in part for the severity of the growth deficiency. This observation is of interest for two reasons. First, these deletions could be a clue in the search for a gene responsible for growth hormone deficiency/midline defects. Second, it shows the importance of molecular cytogenetics in the study of de novo apparently balanced translocation with abnormal phenotype.     

15q24.1 BP4-BP1 microdeletion unmasking paternally inherited functional polymorphisms combined with distal 15q24.2q24.3 duplication in a patient with epilepsy,psychomotor delay,overweight, ventricular arrhythmia

15q24 microdeletion and microduplication syndromes are genetic disorders caused by non-allelic homologous recombination between low-copy repeats (LCRs) in the 15q24 chromosome region. Individuals with 15q24 microdeletion and microduplication syndromes share a common 1.2 Mb critical interval, spanning from LCR15q24B to LCR15q24C. Patients with 15q24 microdeletion syndrome exhibit distinct dysmorphic features, microcephaly, variable developmental delay, multiples congenital anomalies while individuals with reciprocal 15q24 microduplication syndrome show mild developmental delay, facial dysmorphism associated with skeletal and genital abnormalities. We report the first case of a 10 year-old girl presenting mild developmental delay, psychomotor retardation, epilepsy, ventricular arrhythmia, overweight and idiopathic central precocious puberty. 180K array-CGH analysis identified a 1.38 Mb heterozygous interstitial 15q24.1 BP4-BP1 microdeletion including HCN4 combined with a concomitant 2.6 Mb heterozygous distal 15q24.2q24.3 microduplication. FISH analysis showed that both deletion and duplication occurred de novo in the proband. Of note, both copy number imbalances did not involve the 1.2 Mb minimal deletion/duplication critical interval of the 15q24.1q24.2 chromosome region (74.3–75.5 Mb). Sequencing of candidate genes for epilepsy and obesity showed that the proband was hemizygous for paternal A-at risk allele of BBS4 rs7178130 and NPTN rs7171755 predisposing to obesity, epilepsy and intellectual deficits. Our study highlights the complex interaction of functional polymorphisms and/or genetic variants leading to variable clinical manifestations in patients with submicroscopic chromosomal aberrations.     

Molecular characterization of a patient with an interstitial 1q deletion [del(1)(q24.1q25.3)] and distinctive skeletal abnormalities

Here we report on a patient with an interstitial deletion on the long(q) arm of chromosome 1 who presents with a unique constellation of anomalies including brachydactyly type E, Müllerian agenesis, growth hormone deficiency, as well as other abnormalities. We present the clinical details of this patient's presentation, the skeletal findings, and provide characterization of the deletion at the molecular level. We postulate that these skeletal anomalies are distinctive to 1q deletions involving the 1q24q25 region.     

Constitutional 11q14-q22 chromosome deletion syndrome in a child with neuroblastoma MYCN single copy

Constitutional 11q deletion is a chromosome imbalance possibly found in MCA/MR patients analyzed for chromosomal anomalies. Its role in determining the phenotype depends on extension and position of deleted region. Loss of heterozygosity of 11q (region 11q23) is also associated with neuroblastoma, the most frequent extra cranial cancer in children. It represents one of the most frequent cytogenetic abnormalities observed in the tumor of patients with high-risk disease even if germline deletion of 11q in neuroblastoma is rare. Hereby, we describe a 18 months old girl presenting with trigonocephaly and dysmorphic facial features, including hypotelorism, broad depressed nasal bridge, micrognathia, synophrys, epicanthal folds, and with a stage 4 neuroblastoma without MYCN amplification, carrying a germline 11q deletion (11q14.1-q22.3), outside from Jacobsen syndrome and from neuroblastoma 11q critical regions. The role of 11q deletion in determining the clinical phenotype and its association with neuroblastoma development in the patient are discussed.     

Interstitial deletion of chromosome 1q [del(1)(q24q25.3)] identified by fluorescence in situ hybridization and gene dosage analysis of apolipoprotein A-II,coagulation factor V,and antithrombin III

We report on a 12-month-old Japanese boy with an interstitial deletion of the long-arm of chromosome 1 and meningomyelocele, hydrocephalus, anal atresia, atrial septal defect, left renal agenesis, bilateral cryptorchidism, talipes equinovarus, low birth weight, growth/developmental retardation, and many minor anomalies. By conventional GTG-banding, his karyotype was first interpreted as 46,XY,del(1)(q23q24), but it was corrected as 46,XY.ish del(1)(q24q25.3) by fluorescence in situ hybridization using 11 known cosmid clones as probes. His serum levels of apolipoprotein A-II (gene symbol: APOA2, previously assigned to 1q21-q23) and coagulation factor V (F5, 1q21-q25) were normal, while serum concentration and activity of antithrombin III (AT3, 1q23-q25.1) was low. The results indicated that localization of APOA2 and F5 are proximal to the deleted region and AT3 is located within the deletion extent in the patient. Am. J. Med. Genet. 68:207–210, 1997 © 1997 Wiley-Liss, Inc.     

Terminal Deletion of 11q with Significant Late-Onset Combined Immune Deficiency

Purpose

We report a 45-year old female adult patient with terminal deletion of chromosome 11q resulting in clinical phenotype of late-onset combined immunodeficiency.

Methods

We describe the clinical phenotype and discuss the similarities between our patient and those with chromosome 22q11.2 deletion syndrome. Immunological evaluation included immunoglobulin levels, vaccine responses, number and function of T, NK and B cell subsets and comparative genomic hybridization test of blood and fibroblasts.

Results

The patient suffered from recurrent pneumococcal pneumonia and genital and cutaneous condylomas. She had a history of learning difficulties, dysmorphic features, autoimmune thyroiditis, chronic thrombocytopenia and severe asthma. We found Paris-Trousseau type thrombocytopenia, B-, T- and NK-lymphopenia, T cell oligoclonality and IgG hypogammaglobulinemia with inability to respond to pneumococcal polysaccharide, tetanus and diphtheria vaccines. A terminal deletion of chromosome 11q compatible with partial Jacobsen syndrome was found.

Conclusions

This confirms Jacobsen syndrome as a chromosome deletion syndrome able to cause combined immunodeficiency.     

Microcephaly, jejunal atresia, aberrant right bronchus, ocular anomalies, and XY sex reversal

We describe a 34-year-old male patient with Jacobsen syndrome associated with a broad spectrum of anomalies and an increased susceptibility to infections. Features commonly seen in Jacobsen syndrome were short stature, mental retardation, congenital heart disease, cryptorchidism, strabismus, distal hypospadia glandis, and mild thrombocytopenia. Chromosome analysis disclosed a mosaic 46,XY,del(11)(q24.1)/46,XY karyotype with a very low percentage of normal cells. In addition, transverse upper limb defect, imperforate anus, and hearing impairment were noted. Cellular anomalies include functional impairment and deficiency of T-helper cells, and a low serum immunoglobulin M (IgM)-level. The presence of a transverse limb defect and primary immunodeficiency has not been reported previously in Jacobsen syndrome.     

Interstitial deletion of the long arm of chromosome 4 [del(4)(q21.22q23)] and a liver tumor

We report on a boy with proximal interstitial deletion of chromosome 4, del(4)(q21. 22q23). The patient was born at term with a low birth weight, flat nasal bridge, micrognathia, wide-spaced nipples, clinodactyly of fifth fingers, overlapping fingers, postaxial polydactyly of the right foot, micropenis, hypospadias, a dermal sinus, and cardiac malformations. He developed psychomotor retardation, seizures, and a liver tumor with an increased serum α-fetoprotein level and rapid growth. The patient carried a deletion of chromosome 4 involving the 4q21-q22 region that was reported to form a unique syndrome. The absence of central nervous system overgrowth and the presence of a malignant liver tumor are unique to our patient, compared to others with the 4q21-q22 deletion syndrome. The clinical manifestations and relationship between the liver tumor and chromosomal anomaly are discussed. Am. J. Med. Genet. 78:291–293, 1998. © 1998 Wiley-Liss, Inc.     

Syndrome of congenital cataracts, sensorineural deafness, Down syndrome-like facial appearance, short stature, and mental retardation: two additional cases

An apparently new syndrome of congenital cataracts, sensorineural deafness, Down syndrome-like facial appearance, short stature, and mental retardation was described by Gripp et al. 1996. The authors reported on two unrelated patients with congenital cataracts, sensorineural deafness, distinctive facial appearance, mental retardation, postnatal short stature, and skeletal changes. We report on two additional patients with findings most similar to the reported patients by Gripp et al. 1996, including bilateral congenital cataracts, hearing loss, craniofacial abnormalities, short stature, skeletal abnormalities, and developmental delay. Both of the patients reported herein had chromosome microarray analysis, which showed normal results in Patient 2 but abnormal results in Patient 1 and his mother who both had a chromosome 11q25 subtelomere deletion. Patient 1 and his mother's findings are atypical for the common findings reported in Jacobsen syndrome (11q terminal deletion syndrome), and consistent with the patients reported by Gripp et al. 1996. The etiology for these cases has been unknown. The microarray results on Patient 1 suggest that the other patients with findings of developmental delay, short stature, congenital cataracts, sensorineural hearing loss, and similar craniofacial features may have either a microdeletion of chromosome 11q terminal region or haploinsufficiency of a gene localized to this region.     

Localization of Jacobsen Syndrome Breakpoints on a 40-Mb Physical Map of Distal Chromosome 11q

Jacobsen syndrome is a haploinsufficiency disorder caused, most frequently by terminal deletion of part of the long arm of chromosome 11, with breakpoints in 11q23.3–11q24.2. Inheritance of an expanded p(CCG)_n trinucleotide repeat at the folate-sensitive fragile site FRA11B has been implicated in the generation of the chromosome breakpoint in several Jacobsen syndrome patients. The majority of such breakpoints, however, map distal to this fragile site and are not linked with its expression. To characterize these distal breakpoints and ultimately to further investigate the mechanisms of chromosome breakage, a 40-Mb YAC contig covering the distal long arm of chromosome 11 was assembled. The utility of the YAC contig was demonstrated in three ways: (1) by rapidly mapping the breakpoints from two new Jacobsen syndrome patients using FISH; (2) by demonstrating conversion to high resolution PAC contigs after direct screening of PAC library filters with a YAC clone containing a Jacobsen syndrome breakpoint; and (3) by placing 23 Jacobsen syndrome breakpoints on the physical map. This analysis has suggested the existence of at least two new Jacobsen syndrome breakpoint cluster regions in distal chromosome 11.     

Prenatal diagnosis of mosaicism for 11q terminal deletion

The phenotype of 11q terminal deletion also known as Jacobsen syndrome is a clinically well known entity whose diagnosis in infancy and childhood is based on clinical examination, hematological and cytogenetic findings. Hematological features in Jacobsen syndrome are very similar to those reported in Paris–Trousseau syndrome (PTS) which is also associated with11q terminal deletion. Karyotype analysis shows a variable terminal deletion from 11q23 sub-band extending to the telomere. Most often in patients with Jacobsen syndrome, this chromosomal deletion is present in all metaphases. We report on the identification of a distal 11q deletion in mosaic (20% of deleted cells) in a fetus ascertained after amniocentesis for maternal serum screening test indicative for Down syndrome. The present case is the third prenatal diagnosis of a mosaic for a distal 11q deletion with the lowest mosaicism rate. The 2D-ultrasound examination and cord blood hematological studies were useful to estimate the prognosis at term, considering the contribution of the mosaicism rate to the phenotypic variability in Jacobsen syndrome. The identification of mosaicism for distal 11q deletion is a very rare event in prenatal diagnosis. This case illustrates the complexity in genetic counselling for prenatally ascertained partial monosomy 11qter in mosaic.     

An infant with deletion of the distal long arm of chromosome 15 (q26.1----qter) and loss of insulin-like growth factor 1 receptor gene.

We report on an infant with a previously undescribed chromosome 15 deletion (q26.1----qter) and compare the clinical findings with those of 7 reported patients with deletions of distal 15q, as well as ring chromosome 15 syndrome patients. Most of the patients with deletions of distal 15q, including our patient, have intrauterine growth retardation (IUGR), microcephaly, abnormal face and ears, micrognathia, highly arched palate, renal abnormalities, lung hypoplasia, failure to thrive, and developmental delay/mental retardation. Several genes have been assigned to the 15q25----qter region, including insulin-like growth factor 1 receptor (IGF1R). DNA analysis from our patient documented the loss of one IGF1R gene copy. Our study further localizes the IGF1R gene distal to the 15q26.1 band. It is interesting to speculate that the severe IUGR and postnatal growth deficiency of our patient and other patients with similar chromosome 15 deletions are related to the loss of an IGF1R gene copy which may lead to an abnormal number and/or structure of the receptors.     

An infant with deletion of the distal long arm of chromosome 15 (q26.1→qter) and loss of insulin-like growth factor 1 receptor gene

We report on an infant with a previously undescribed chromosome 15 deletion (q26.1→qter) and compare the clinical findings with those of 7 reported patients with deletions of distal 15q, as well as ring chromosome 15 syndrome patients. Most of the patients with deletions of distal 15q, including our patient, have intrauterine growth retardation (IUGR), microcephaly, abnormal face and ears, micrognathia, highly arched palate, renal abnormalities, lung hypoplasia, failure to thrive, and developmental delay/mental retardation. Several genes have been assigned to the 15q25→qter region, including insulin-like growth factor 1 receptor (IGF1R). DNA analysis from our patient documented the loss of one IGF1R gene copy. Our study further localizes the IGF1R gene distal to the 15q26.1 band. It is interesting to speculate that the severe IUGR and postnatal growth deficiency of our patient and other patients with similar chromosome 15 deletions are related to the loss of an IGF1R gene copy which may lead to an abnormal number and/or structure of the receptors.     

‘Deletion rescue’ by mitotic 11q uniparental disomy in a family with recurrence of 11q deletion Jacobsen syndrome

We describe a family with recurrent 11q23‐qter deletion Jacobsen syndrome in two affected brothers, with unique mosaic deletion ‘rescue’ through development of uniparental disomy (UPD) in the mother and one of the brothers. Inheritance studies show that the deleted chromosome is of maternal origin in both boys, and microarray shows a break near the ASAM gene. Parental lymphocyte chromosomes were normal. However, the mother is homozygous in lymphocytes for all loci within the deleted region in her sons, and presumably has UPD for this region. In addition, she is mosaic for the 11q deletion seen in her sons at a level of 20–30% in skin fibroblasts. We hypothesize that one of her #11 chromosomes shows fragility, that breakage at 11q23 occurred with telomeric loss in some cells, but ‘rescue’ from the deletion occurred in most cells by the development of mitotic UPD. She apparently carries the 11q deletion in her germ line resulting in recurrence of the syndrome. The older son is mosaic for the 11q cell line (70–88%, remainder 46,XY), and segmental UPD11 ‘rescue’ apparently also occurred in his cytogenetically normal cells. This is a novel phenomenon restoring disomy to an individual with a chromosomal deletion.     

Giant platelets in a case of deletion 11q24‐qter confirmed by fluorescence in situ hybridization

Here we report the association of giant platelets and an increase in platelet volume in a 19‐month‐old black female with de novo del 11q24‐qter. The deletion, which was visible on karyotype, was further confirmed and more precisely localized by fluorescence in situ hybridization studies (FISH) that showed the deletion to lie distal to the MLL gene region (11q23). Clinically, the case presented less severe symptoms than Jacobsen syndrome‐the well known partial deletion of the distal end of chromosome 11. Platelet glycoproteins CD 41, CD 42a, C 42b, CD 61, and PAC‐1 were also assayed and found to be normally expressed. To our knowledge, giant platelets are described for the first time in the relevant deleted region. © 2002 Wiley‐Liss, Inc.     

Neuroblastoma in a boy with MCA/MR syndrome,deletion 11q,and duplication 12q

Deletion 11q23→qter and duplication 12q23→qter are described in a boy with neuroblastoma, multiple congenital anomalies, and mental retardation. The patient has clinical manifestations of 11q deletion and 12q duplication syndromes. The possible involvement of the segment 11q23→24 in the cause of the neuroblastoma is discussed. © 1995 Wiley-Liss, Inc.