Distal 11q monosomy. The typical 11q monosomy syndrome is due to deletion of subband 11q24.1

11q24.2q24.3 microdeletion in two families presenting features of Jacobsen syndrome, without intellectual disability: Role of FLI1, ETS1, and SENCR long noncoding RNA

This report presents two families with interstitial 11q24.2q24.3 deletion, associated with malformations, hematologic features, and typical facial dysmorphism, observed in Jacobsen syndrome (JS), except for intellectual disability (ID). The smallest 700 Kb deletion contains only two genes: FLI1 and ETS1, and a long noncoding RNA, SENCR, narrowing the minimal critical region for some features of JS. Consistent with recent literature, it adds supplemental data to confirm the crucial role of FLI1 and ETS1 in JS, namely FLI1 in thrombocytopenia and ETS1 in cardiopathy and immune deficiency. It also supports that combined ETS1 and FLI1 haploinsufficiency explains dysmorphic features, notably ears, and nose anomalies. Moreover, it raises the possibility that SENCR, a long noncoding RNA, could be responsible for limb defects, because of its early role in endothelial cell commitment and function. Considering ID and autism spectrum disorder, which are some of the main features of JS, a participation of ETS1, FLI1, or SENCR cannot be excluded. But, considering the normal neurodevelopment of our patients, their role would be either minor or with an important variability in penetrance. Furthermore, according to literature, ARHGAP32 and KIRREL3 seem to be the strongest candidate genes in the 11q24 region for other Jacobsen patients.

Structural Genome Variations Related to Craniosynostosis

Craniosynostosis refers to a condition during early development in which one or more of the fibrous sutures of the skull prematurely fuse by turning into bone, which produces recognizable patterns of cranial shape malformations depending on which suture(s) are affected. In addition to cases with isolated cranial dysmorphologies, craniosynostosis appears in syndromes that include skeletal features of the eyes, nose, palate, hands, and feet as well as impairment of vision, hearing, and intellectual development. Approximately 85% of the cases are nonsyndromic sporadic and emerge after de novo structural genome rearrangements or single nucleotide variation, while the remainders consist of syndromic cases following mendelian inheritance. By karyotyping, genome wide linkage, and CNV analyses as well as by whole exome and whole genome sequencing, numerous candidate genes for craniosynostosis belonging to the FGF, Wnt, BMP, Ras/ERK, ephrin, hedgehog, STAT, and retinoic acid signaling pathways have been identified. Many of the craniosynostosis-related candidate genes form a functional network based upon protein-protein or protein-DNA interactions. Depending on which node of this craniosynostosis-related network is affected by a gene mutation or a change in gene expression pattern, a distinct craniosynostosis syndrome or set of phenotypes ensues. Structural variations may alter the dosage of one or several genes or disrupt the genomic architecture of genes and their regulatory elements within topologically associated chromatin domains. These may exert dominant effects by either haploinsufficiency, dominant negative partial loss of function, gain of function, epistatic interaction, or alteration of levels and patterns of gene expression during development. Molecular mechanisms of dominant modes of action of these mutations may include loss of one or several binding sites for cognate protein partners or transcription factor binding sequences. Such losses affect interactions within functional networks governing development and consequently result in phenotypes such as craniosynostosis. Many of the novel variants identified by genome wide CNV analyses, whole exome and whole genome sequencing are incorporated in recently developed diagnostic algorithms for craniosynostosis.

de novo interstitial deletions at the 11q23.3-q24.2 region

Background

Jacobsen syndrome (JBS) is a contiguous gene deletion syndrome involving 11q terminal deletion. Interstitial deletions at distal 11q are rare and their contributions to the clinical phenotype of JBS are unknown.

Case presentation

We presented the chromosome microarray (CMA) data and the clinical features of two individuals carrying a non-overlapping de novo deletion each at the 11q23.3-q24.2 region in an effort to analyze the correlation between region of deletion at 11q and phenotype. Both deletions are likely pathogenic for patient’s condition. The deletion at 11q23.3q24.1 is associated with short stature, relative microcephaly, failure to thrive, hypotonia and sleeping disorder. The deletion at 11q24.2 involves HEPACAM and our patient’s clinical presentation (relative macrocephaly, abnormal MRI, mild developmental delay and seizure) is not inconsistent with Megalencephalic leukoencephalopathy with subcortical cysts 2B.

Conclusions

Our finds support the notion that more than one critical region at 11q23.3-qter are responsible for the variable clinical presentation of JBS, thus JBS is a true contiguous gene deletion syndrome where multiple loci contributed to the clinical characteristics of JBS. Small interstitial deletions at 11q23.3-q24.2 and their associated unique features also suggest emerging novel genomic disorders.

Electronic supplementary material

The online version of this article (doi:10.1186/s13039-016-0247-7) contains supplementary material, which is available to authorized users.

A novel case of bilateral high myopia, cataract, and total retinal detachment associated with interstitial 11q deletion

PURPOSE

Jacobsen syndrome, also known as 11q deletion syndrome, is a rare condition characterized by multiple anomalies, including developmental delay, cardiac abnormalities, blood dyscrasias, distal limb abnormalities, craniofacial anomalies, and variable ophthalmic manifestations. The syndrome's phenotype is due to a terminal deletion and is usually severely debilitating, frequently associated with fatality. Interstitial deletions, not involving the terminal end, have been associated with a more variable and less severe phenotype.

METHODS

Herein, we describe a case of interstitial 11q deletion in a 16 year-old female with associated systemic and craniofacial abnormalities as well as a novel combination of ocular findings, specifically strabismus, high myopia, bilateral cataracts, and bilateral total retinal detachments.

RESULTS

This case report highlights the necessity for a detailed ophthalmic examination of patients with both interstitial and terminal deletions of the long arm of chromosome 11.

Detailed molecular and clinical investigation of a child with a partial deletion of chromosome 11 (Jacobsen syndrome)

Background

Jacobsen syndrome (JBS) is a rare chromosomal disorder leading to multiple physical and mental impairment. This syndrome is caused by a partial deletion of chromosome 11, especially subband 11q24.1 has been proven to be involved. Clinical cases may easily escape diagnosis, however pancytopenia or thrombocytopenia may be indicative for JBS.

Results

We report a 7.5 years old boy presenting with speech development delay, hearing impairment and abnormal platelet function. High resolution SNP oligonucleotide microarray analysis revealed a terminal deletion of 11.4 Mb in size, in the area 11q24.1-11qter. This specific deletion encompasses around 170 genes. Other molecular techniques such as fluorescence in situ hybridization and multiplex ligation-dependent probe amplification were used to confirm the array-result.

Discussion

Our results suggest that the identification and detailed analysis of similar patients with abnormal platelet function and otherwise mild clinical features will contribute to identification of more patients with 11q deletion and JBS.

Jacobsen syndrome

Jacobsen syndrome is a MCA/MR contiguous gene syndrome caused by partial deletion of the long arm of chromosome 11. To date, over 200 cases have been reported. The prevalence has been estimated at 1/100,000 births, with a female/male ratio 2:1. The most common clinical features include pre- and postnatal physical growth retardation, psychomotor retardation, and characteristic facial dysmorphism (skull deformities, hypertelorism, ptosis, coloboma, downslanting palpebral fissures, epicanthal folds, broad nasal bridge, short nose, v-shaped mouth, small ears, low set posteriorly rotated ears). Abnormal platelet function, thrombocytopenia or pancytopenia are usually present at birth. Patients commonly have malformations of the heart, kidney, gastrointestinal tract, genitalia, central nervous system and skeleton. Ocular, hearing, immunological and hormonal problems may be also present. The deletion size ranges from approximately 7 to 20 Mb, with the proximal breakpoint within or telomeric to subband 11q23.3 and the deletion extending usually to the telomere. The deletion is de novo in 85% of reported cases, and in 15% of cases it results from an unbalanced segregation of a familial balanced translocation or from other chromosome rearrangements. In a minority of cases the breakpoint is at the FRA11B fragile site. Diagnosis is based on clinical findings (intellectual deficit, facial dysmorphic features and thrombocytopenia) and confirmed by cytogenetics analysis. Differential diagnoses include Turner and Noonan syndromes, and acquired thrombocytopenia due to sepsis. Prenatal diagnosis of 11q deletion is possible by amniocentesis or chorionic villus sampling and cytogenetic analysis. Management is multi-disciplinary and requires evaluation by general pediatrician, pediatric cardiologist, neurologist, ophthalmologist. Auditory tests, blood tests, endocrine and immunological assessment and follow-up should be offered to all patients. Cardiac malformations can be very severe and require heart surgery in the neonatal period. Newborns with Jacobsen syndrome may have difficulties in feeding and tube feeding may be necessary. Special attention should be devoted due to hematological problems. About 20% of children die during the first two years of life, most commonly related to complications from congenital heart disease, and less commonly from bleeding. For patients who survive the neonatal period and infancy, the life expectancy remains unknown.

Submicroscopic deletions of 11q24-25 in individuals without Jacobsen syndrome: re-examination of the critical region by high-resolution array-CGH

BACKGROUND

Jacobsen syndrome is a rare contiguous gene disorder that results from a terminal deletion of the long arm of chromosome 11. It is typically characterized by intellectual disability, a variety of physical anomalies and a distinctive facial appearance. The 11q deletion has traditionally been identified by routine chromosome analysis. Array-based comparative genomic hybridization (array-CGH) has offered new opportunities to identify and refine chromosomal abnormalities in regions known to be associated with clinical syndromes.

RESULTS

Using the 1 Mb BAC array (Spectral Genomics), we screened 70 chromosomally normal children with idiopathic intellectual disability (ID) and congenital abnormalities, and identified five cases with submicroscopic abnormalities believed to contribute to their phenotypes. Here, we provide detailed molecular cytogenetic descriptions and clinical presentation of two unrelated subjects with de novo submicroscopic deletions within chromosome bands 11q24-25. In subject 1 the chromosome rearrangement consisted of a 6.18 Mb deletion (from 128.25-134.43 Mb) and an adjacent 5.04 Mb duplication (from 123.15-128.19 Mb), while in subject 2, a 4.74 Mb interstitial deletion was found (from 124.29-129.03 Mb). Higher resolution array analysis (385 K Nimblegen) was used to refine all breakpoints. Deletions of the 11q24-25 region are known to be associated with Jacobsen syndrome (JBS: OMIM 147791). However, neither of the subjects had the typical features of JBS (trigonocephaly, platelet disorder, heart abnormalities). Both subjects had ID, dysmorphic features and additional phenotypic abnormalities: subject 1 had a kidney abnormality, bilateral preauricular pits, pectus excavatum, mild to moderate conductive hearing loss and behavioral concerns; subject 2 had macrocephaly, an abnormal MRI with delayed myelination, fifth finger shortening and squaring of all fingertips, and sensorineural hearing loss.

CONCLUSION

Two individuals with ID who did not have the typical clinical features of Jacobsen syndrome were found to have deletions within the JBS region at 11q24-25. Their rearrangements facilitate the refinement of the JBS critical region and suggest that a) deletion of at least 3 of the 4 platelet function critical genes (ETS-1, FLI-1 and NFRKB and JAM3) is necessary for thrombocytopenia; b) one of the critical regions for heart abnormalities (conotruncal heart defects) may lie within 129.03 - 130.6 Mb; c) deletions of KCNJ1 and ADAMTS15 may contribute to the renal anomalies in Jacobsen Syndrome; d) the critical region for MRI abnormalities involves a region from 124.6 - 129.03 Mb. Our results reiterate the benefits of array-CGH for description of new phenotype/genotype associations and refinement of previously established ones.

Platelet storage pool deficiency in Jacobsen syndrome

Jacobsen syndrome and Paris-Trousseau Syndrome share similar congenital anomalies, thrombocytopenia, giant platelet alpha granules resulting from fusion of smaller organelles, and an 11q terminal deletion at 11q23.3. Similarities in the two cohorts have suggested that the Paris-Trousseau Syndrome is a variant of Jacobsen syndrome, or the same disorder. The present study has pointed out a significant difference between the two syndromes. Platelets from six patients with Jacobsen syndrome were markedly diminished in serotonin adenine nucleotide rich dense bodies, indicating the presence of platelet storage pool deficiency. Since platelet dense bodies are reported to be normal in size, number and distribution in the Paris-Trousseau Syndrome, the presence of platelet storage pool deficiency in six patients evaluated in the present study may distinguish the two disorders.

A de novo subtelomeric monosomy 11q (11q24.2-qter) and trisomy 20q (20q13.3-qter) in a girl with findings compatible with Jacobsen syndrome: case report and review

We report on a 2-year-old dysmorphic girl with prenatal and postnatal growth deficiency, cardiopathy, left-sided hydronephrosis due to pyelourethral junction stenosis, frequent respiratory infections and psychomotor retardation, in whom a de novo unbalanced submicroscopic translocation (11q;20q) was detected by subtelomeric multiplex ligation-dependent probe amplification and fluorescence in situ hybridization analyses. Additional fluorescence in situ hybridization studies with locus-specific BAC probes and analyses with microsatellite markers revealed that this translocation resulted in a paternal chromosome 11q terminal deletion of approximately 8.9 Mb and a subtelomeric 20q duplication of approximately 3.7 Mb. A subtelomeric 20q trisomy has only been reported in four cases so far. A subtelomeric 11q deletion has been clinically reported in 18 patients. We review the clinical phenotype of these patients. We suggest that patients with a subterminal (11q24.2/25-qter) deletion may present with features of the well-known phenotype of terminal 11q deletion or Jacobsen syndrome.

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.

Association of Jacobsen syndrome and bipolar affective disorder in a patient with a de novo 11q terminal deletion

We report on a young woman with Jacobsen syndrome (JBS) who was admitted to our psychiatric department because of a bipolar affective disorder (BPAD). Chromosome analysis was performed due to the fact that she had mental retardation, short stature, and subtle facial anomalies. A deletion of the distal long arm of chromosome 11 was found. A detailed mapping of the deletion breakpoint by quantitative real time PCR revealed a true terminal 11q deletion of approximately 8 Mb corresponding to the karyotype 46,XX,del(11)(q24.2). Polymorphic DNA marker analysis showed that the deletion is located on the paternal chromosome. Additionally, laboratory investigations revealed a low platelet count and magnetic resonance imaging of the brain showed white matter T2 hyperintensities in frontotemporal regions, which are unlikely to result from a demyelinating process as indicated by localized proton magnetic resonance spectroscopy. To our knowledge, this is the first report describing a BPAD in a case with JBS.

Primary immunodeficiency in combination with transverse upper limb defect and anal atresia in a 34-year-old patient with Jacobsen syndrome

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.

Ocular findings in Jacobsen syndrome

PURPOSE

To discuss the ophthalmic findings and their clinical significance in 10 new cases of Jacobsen syndrome (mental retardation, craniofacial anomalies, congenital heart defects, and blood dyscrasias) and to review the ophthalmic findings in all previously reported cases in the literature.

METHODS

Ten new cases of Jacobsen syndrome were collected and studied prospectively for detection of abnormal ophthalmologic examination findings. A total of 63 previously reported cases were identified from Medline and analyzed for ophthalmologic abnormalities.

RESULTS

The most common ophthalmologic findings in the new cases of Jacobsen syndrome included strabismus (90.0%), refractive error (90.0%), and ptosis (70.0%). Facial dysmorphism was also common and included hypertelorism, epicanthal folds, and down-slanting palpebral fissures. Uncommon ophthalmic findings included 5 patients with retinal vascular tortuosity, 1 with glaucoma, and 3 with amblyopia. In 63 cases reviewed, 36 reported ophthalmologic abnormalities. The most common findings included facial anomalies and ptosis. Only 5 of the 63 patients had evidence of strabismus, and none were reported to have retinal vascular tortuosity.

CONCLUSIONS

To prevent unnecessary vision loss in children with Jacobsen syndrome, proper screening for amblyogenic factors is imperative. We recommend a baseline complete ophthalmologic examination with subsequent follow-up examinations depending on the particular findings noted during the initial screening visit.

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.

Girl with combined cellular immunodeficiency, pancytopenia, malformations, deletion 11q23.3 --> qter, and trisomy 8q24.3 --> qter

We describe here a 3-year-old girl demonstrating combined cellular immunodeficiency of B- and T-cells, pancytopenia, multiple anomalies, and severe mental retardation. Cytogenetic analysis and fluorescent in situ hybridization (FISH) indicated an unbalanced translocation of chromosomes 8q and 11q, resulting in monosomy 11q23.3-qter and trisomy 8q24.3-qter. The association of cellular immunodeficiency and partial deletion 11q and/or partial trisomy 8q has not been described previously; however, the 11q deletion has been reported with humoral immunodeficiency or pancytopenia. Some one-third to one-half of patients with partial monosomy 11q were reported to have pancytopenia, which has been related to the absence of the 11q23-q24 region. Our case narrows down the critical interval for thrombo- or pancytopenia to 11q23.3-q24 and excludes both the ATM (which resides on 11q23.1) and the MLL genes as possible candidate genes. We are proposing that haploinsufficiency of the NFRKB gene on 11q24-q25 and/or the ETS-1 proto-oncogene on 11q24 may have caused or contributed to the immunodeficiency (decreased levels of B- and T-lymphocytes) in our patient.

Detecting rearrangements in children using subtelomeric FISH and SKY

The etiology of mental retardation (MR), often presenting as developmental delay in childhood, is unknown in approximately one-half of cases. G-banding is the standard method for investigating those suspected of having a chromosomal etiology; however, detection of structural abnormalities is limited by the size and pattern of the G-bands involved. Rearrangements involving subtelomeric regions have been shown to cause MR and this has generated interest in investigating the prevalence of these rearrangements using telomere-specific probes. In addition, because cryptic interchromosomal rearrangements may not be small or confined to chromosomal ends, spectral karyotyping (SKY) using chromosome-specific painting probes may be of value. We report here a study using these two FISH-based techniques in 50 children with idiopathic MR or developmental delay and normal GTG-banded karyotypes. Our objective was to assess the prevalence of cryptic rearrangements in this population using subtelomeric FISH and SKY. Three rearrangements were detected by subtelomeric FISH: a derivative 5 from a maternal t(5;21); a recombinant 11 from a paternal pericentric inversion; and a 2q deletion that was also present in the mother. Only the derivative 5 was detected by SKY. SKY did not detect any interstitial interchromosomal rearrangement. The prevalence of clinically significant cryptic rearrangements by subtelomeric FISH and SKY was thus 4% (95% confidence interval 0.5-13.7) and 2% (95% CI 0.05-10.7), respectively. This study supports the view that G-banding does not detect all clinically significant chromosomal abnormalities and that subtelomeric FISH and SKY can detect some of these abnormalities.

Paris-Trousseau syndrome platelets in a child with Jacobsen's syndrome

The thrombocytopenia in an infant with clinical features of Jacobsen's syndrome characterized by multiple congenital anomalies, cardiac defects, psychomotor retardation, and deletion of chromosome 11 at 11q23.3 has been evaluated. Study of his platelets in the electron microscope revealed giant alpha granules in his cells identical in appearance to those reported in the family with Paris-Trousseau syndrome. As a result, the Paris-Trousseau syndrome appears to be a variant of the Jacobsen syndrome, and the thrombocytopenia observed in all cases of chromosome 11q23.3 deletion due to dysmegakaryopoieses. Giant alpha granules are frequently observed in normal platelets during long-term storage and may form in Jacobsen and Paris-Trousseau platelets during prolonged residence in the bone marrow.

Prenatal diagnosis of de novo distal 11q deletion associated with sonographic findings of unilateral duplex renal system, pyelectasis and orofacial clefts

In utero diagnosis of de novo distal 11q deletion associated with renal and orofacial malformations has not been previously described. We present a 35-year-old pregnant woman with prenatal sonographic findings of a unilateral duplex renal system, pyelectasis and orofacial clefts at 20 weeks' gestation. Both genetic amniocentesis and postnatal cytogenetic analysis revealed de novo 46,XX,del(11)(q23). After birth, the fetus manifested a dysmorphic phenotype correlated with del(11q) syndrome. Genetic marker analysis showed a paternally derived distal deletion of chromosome 11q and a breakpoint centromeric to D11S1341. The present case represents the earliest prenatal diagnosis of a duplex renal system, pyelectasis and an additional feature of orofacial clefts associated with distal 11q deletion. Prenatal sonographic detection of a duplex renal system, pyelectasis and orofacial clefts should warrant a careful assessment of fetal anatomy and prompt cytogenetic analysis looking for chromosomal aberrations.

A case of discordant related abnormal karyotypes from chorionic villi and amniocytes

A case of three discordant cell lines in prenatal diagnosis is described, of which two were abnormal related structural abnormalities of chromosome 11. One of the abnormal cell lines was seen in all metaphases examined from direct preparations of chorionic villi, the cultured preparations showing an apparently normal male karyotype; the other abnormal cell line was seen in conjunction with a normal cell line in cultured amniocytes. Prenatal diagnosis offered solely on chorionic villus sampling would have yielded a mistakenly normal result on the basis of established criteria for distinguishing true mosaicism from confined placental mosaicism.

Reciprocal translocation 4;11 with both adjacent-1 segregants viable within a family

We describe a family carrying a balanced 4;11 translocation in which both adjacent-1 segregants are viable. The proband had an unbalanced karyotype: 46,XY,der(11)t(4;11)(q34.3;q23.1)mat. At 8.5 years of age he showed trigonocephaly, hypertelorism, epicanthal folds, down-slanting palpebral fissures, low-set ears, anteverted nares, down-turned carp-shaped mouth, and bilateral fifth finger clinodactyly. His maternal aunt was also dysmorphic with high-arched palate, short philtrum and mild developmental delay. Her karyotype was 46,XX,der(4)t(4;11)(q34.3;q23.1)pat. Other relatives who likely carried a chromosomally unbalanced segregant were identified from photographs and medical records. We compare the clinical findings in our family with descriptions of other similar karyotypic abnormalities from previous case reports.

Partial deletion of the long arm of chromosome 11: ten Japanese children

The clinical features of partial deletion 11q were correlated with the size of the deleted region. Ten Japanese children with partial deletion of 11q were investigated. They were divided into three groups. Three patients in the first group had interstitial deletions and preserved subband q24.1. Six patients in the second group demonstrated terminal deletion of 11q including subband q24.1, with typical features of 11q- syndrome (Jacobsen syndrome). The third group included only one patient, who had terminal deletion of 11q without characteristics of typical 11q- syndrome. Prominent features of patients in the first group included severe mental and motor developmental delay, seizures, cleft lip and palate, and ophthalmological findings. Patients in the second group showed mild to moderate developmental delays without deterioration. Abnormalities in neuroimages, high intensity in the cerebral white matter in T2-weighted magnetic resonance (MR) images, and recurrent infections were not observed after the age of 7 years. The subject in the third group, with the smallest amount of deleted chromosome, did not show developmental delays, suggesting that some unknown genes related to developmental delays may be located adjacent to subband q24.1. Variation in the deleted parts of 11q resulted in different clinical features in each group.

Jacobsen syndrome: report of a patient with severe eye anomalies, growth hormone deficiency, and hypothyroidism associated with deletion 11 (q23q25) and review of 52 cases

We have evaluated a patient with Jacobsen syndrome. The patient presented with growth retardation, hypotonia, trigonocephaly, telecanthus, downward slanting palpebral fissures, bilateral inferior colobomas (of the iris, choroid, and retina), hydrocephalus, central nervous system (CNS) abnormalities, and an endocardial cushion defect, features commonly seen in Jacobsen syndrome. Endocrine evaluation showed growth hormone deficiency and central hypothyroidism. Chromosome analysis showed a 46,XX,del(11)(q23q25) de novo karyotype. Cytogenetically, the deletion appeared to include most of bands 11q23 and q24 and a portion of q25. Using chromosome specific paint probe, a combination of chromosome 11 centromere, telomere, and region specific cosmid probes from 11q14.1-14.3, 11q23.3, and 11q24.1, we have localised the deletion breakpoint to q24.1. Phenotype-karyotype correlation of patients with Jacobsen syndrome and specific deletions of chromosome 11q has enabled us to suggest that the critical region for this syndrome lies in close proximity to cytogenetic band 11q24. Although growth retardation is a consistent finding in 11q deletion syndrome, the presence of hypothalamic-pituitary hormone deficiency has not been reported previously.

Partial duplication of 3q and distal deletion of 11q in a stillbirth with an omphalocele containing the liver, short limbs, and intrauterine growth retardation

We describe a female stillbirth with duplication of 3q21-->qter and deletion of 11q23-->qter resulting from an unbalanced segregation of a maternal t(3;11) reciprocal translocation. The proband had some of the clinical features consistent with those seen in patients with dup(3q) syndrome or distal del(11q) syndrome. Prenatal sonographic examination showed short limbs, intrauterine growth retardation, and an omphalocele containing the liver.

Two craniosynostotic patients with 11q deletions, and review of 48 cases

Many chromosomal abnormalities have craniofacial manifestations. One such abnormality, partial monosomy of chromosome 11q, is associated with metopic synostosis and resultant trigonocephaly. We reviewed 48 published cases of 11q deletions and translocations. Eighty percent were associated with abnormal head shape. Also commonly found were hypertelorism, ptosis of the eyelids, wide or low nasal bridge, apparently low-set malformed ears, down-turned mouth, micro/retrognathia, digital and cardiac anomalies, and psychomotor retardation. We report on two patients referred for abnormal head shape. The first case had brachycephaly, flat occiput, hypertelorism, and maxillary hypoplasia. Karyotype was 46,XY,del(11)(q24.1-->qter). The second patient had trigonocephaly, hypotelorism, posteriorly angulated ears, horizontal crease below his lower lip, syndactyly, shawl scrotum, cryptorchidism, and inguinal hernias. Karyotype showed partial trisomy of chromosome 4q as well as partial monosomy of 11q [46,XY,11,+der(11)t(4;11) (q31.3;q25)], a combination not previously reported. Deletions of 11q appear to produce a wide spectrum of abnormalities.

Central nervous system abnormalities in chromosome deletion at 11q23

Two Japanese pediatric patients with terminal deletion of the long arm of chromosome 11 are described. Both had the morphological abnormalities of the 11q deletion syndrome, such as prominent epicanthal folds, broad flat nasal bridge with short, upturned nose, short philtrum with carp-shaped mouth, cardiac anomalies and nonprogressive moderate psychomotor developmental delay. Patient 1 is the first case to be reported with 11q deletion with serial magnetic resonance (MR) examinations of cerebral white matter. The initial MR imaging studies demonstrated multiple areas of T1 and T2 prolongation in the cerebral white matter in both patients at the ages of 2 5/12 and 2 1/12 years, respectively. A second MR imaging, performed 1 year after the first in Patient 1, demonstrated slight improvement of the lesions. Neither patient showed clinical deterioration. These results suggest that the lesions were caused by delayed myelination, rather than by demyelination. It is suggested that an unknown factor which is important for myelination is located on the long arm of chromosome 11: perhaps the neural cell adhesion molecule (NCAM).

Monosomy 11q: report of two familial cases and review of the literature

We present four children from two families with the typical 11q- phenotype resulting from an unbalanced segregation of a parental translocation. In the first family, the father had a 46,XY,t(5;11)(q24;q23.3) constitution. The father of the three other children had a 46,XY,t(11;17)(q23;p13) translocation. Despite associated partial deletion, three of the children had a typical 11q- phenotype. The fourth one, whose pregnancy was terminated in the second trimester, had a hypoplastic left heart but no other considered gross anomalies. A review of 36 previous cases, including 5 due to translocations (4 familial rearrangements, and 1 of unknown origin) is given with emphasis on the relationships between break-points and phenotype. Undescribed manifestations in our patients include agenesis of corpus callosum adactyly and malrotation of the gut.

Application of molecular and cytogenetic techniques to the detection of a de novo unbalanced t(11q;21q) in a patient previously diagnosed as having monosomy 21

The occurrence of complete autosomal monosomy in man is extremely rare and generally considered to be incompatible with life. Since the introduction of banding techniques in human cytogenetics, several cases of presumptive monosomy for chromosome 21 have nevertheless been reported. However, it has been suggested that most, if not all, of these cases may represent unbalanced translocations or other structural aberrations resulting in only partial monosomy 21. Here we described a patient in whom full monosomy 21 was initially diagnosed by routine karyotyping. Re-examination with a combination of high resolution banding technique, chromosome painting and DNA polymorphism analysis demonstrated the presence of an unbalanced translocation between the long arms of chromosome 11 and 21, respectively. Consequently, the case was re-classified as a partial monosomy for the proximal long arm of chromosome 21.

Interstitial deletion of the long arm of chromosome 11 determined by fluorescence in situ hybridization

An interstitial deletion, del(11)(q14q22), found in a female infant was examined by fluorescence in situ hybridization with cosmid DNA markers mapped on the long arm of chromosome 11. Three cosmids mapped on 11q14.1-11q22.1 region were not hybridized to the del(11) chromosome, while all the other DNA markers mapped on 11cen-11q14.1 and 11q23.1-11qter region gave hybridization signals on the del(11) chromosome. Cytogenetic analysis after R-banding confirmed an apparent deletion of 11q14-q22, but containing a small R-negative band, a part of 11q22.3 and/or 11q14.1, in the middle part of del(11) chromosome. The karyotype thus was determined to be 46,XX,del(11)(q14.1q22.3).

The 11q- syndrome with mosaic partial deletion of 11q

A female child with mosaic partial deletion of 11q is reported. At 1 month of age she was presented with cogenital glaucoma, trigonocephaly and multiple minor anomalies. She exhibited growth retardation and the typical phenotype of 11q- syndrome. G-banding analysis failed to show any abnormality, although subsequent high resolution banding revealed the abnormal karyotype 46,XX,del(11)(q23.3 q24.2)/46,XX,del(11)(q23.3 q25). This case is a second case of mosaic 11q- syndrome and her karyotype suggests that the region of 11q23.3-11q24.2 is critical in 11q-syndrome. Congenital glaucoma has never been reported as a complication of 11q- syndrome.

Interstitial deletion of the long arm of chromosome 11: report of a case and review of the literature

A 12-month-old female infant with developmental delay, growth retardation, and dysmorphic features including dolichocephaly, telecanthus, ptosis, flat nasal bridge, anteverted nares, high-arched palate, carp-shaped mouth, micro-retrognathia, and low-set and posteriorly rotated ears was found to have an interstitial deletion of chromosome 11 involving bands q14-q22. Immunoblot analysis of her fibroblasts revealed a normal amount of mitochondrial acetoacetyl-coenzyme A thiolase, of which gene locus has been assigned to chromosome 11q22.3-q23.1. This result suggested that the region around the boundary of 11q22.3-q23.1 was intact in this patient.

Molecular detection of a translocation (Y;11) (q11.2;q24) in a 45,X male with signs of Jacobsen syndrome

A 45,X karyotype was found in a boy with dysmorphic features, hypoglycaemia and pancytopenia. DNA analysis showed the presence of the Y-chromosomal DNA sequences SRY, ZFY, DYZ4, DYZ3 and DYS1. Using fluorescent in situ hybridization, we located DYZ4 and DYZ3 on chromosome 11qter and concluded that a de novo translocation (Y;11) (q11.2;q24) with a deletion of 11q24----qter and a deletion of Yq11.2----Yqter were present; Jacobsen syndrome and azoospermia are associated with these deletions. Signs of Jacobsen syndrome were observed in the patient.

Genetic linkage analysis and homology relationships of genes located on human chromosome 11q

We have used DNA polymorphisms detected by probes for 11q to order 16 genes and to determine the genetic distances between them. Our map includes the genes for CD20, tyrosinase, progesterone receptor, stromelysin, collagenase, N-CAM, dopamine-D2 receptor, apolipoproteins AI-CIII-AIV, CD3-epsilon, -delta, and -gamma, porphobilinogen deaminase, thy-1, and ets-1. These genes have previously been sequenced as well as placed on the 11q cytogenetic map, which now makes them anchor points between the cytogenetic, genetic, and physical maps of this region. The ordering and distances between these genes are of immediate use in testing hypotheses of candidate genes for human genetic diseases associated with chromosome 11q. A comparison between our genetic map and similar maps from other species defines regions of homologous synteny that may be useful in mapping human genetic disease genes localized to the 11q region. Analysis of such homology provides additional bases for speculation of the evolutionary histories of gene families in this region.

A primary linkage map of the human chromosome 11q22-23 region

We have constructed a genetic map of the human chromosomal region 11q22-23 by multipoint linkage analysis of 13 DNA polymorphisms that we have condensed into eight loci. An analysis for linkage disequilibrium between tightly linked probe/enzyme systems allows us to make specific recommendations for future DNA typing at these loci. The resulting sex-averaged multipoint map spans approximately 80 cM and differs considerably from previously reported genetic maps of this region. Our mathematically derived "most likely order" of the markers is compatible with physical mapping data using somatic cell hybrids. The known localizations of at least 14 functional genes and several disease loci to 11q22-23, including ataxia telangiectasia, make the mapping of this region especially relevant to studies of disease pathogenesis.

Partial deletion of the long arm of chromosome 11 [del(11)(q23.3----qter)] with abnormal white matter

A patient with partial deletion of the long arm of chromosome 11[del(11)(q23.3----qter)] had macrocephalic trigonocephaly, growth and mental retardation, congenital heart defect, and characteristic facial appearance familiar to that of 33 other reported patients with this deletion. Computed tomography (CT) and magnetic resonance imaging of this infant's brain demonstrated abnormality of the supratentorial white matter. This may represent either deficiency or delay in myelination or possibly a demyelination process. No abnormalities in white matter were described in seven of 33 previously reported patients whose brains were examined by ultrasound, CT, or autopsy.