A de novo translocation t(3;17)(q26.3;q23.1) in a child with Cornelia de Lange syndrome

Short-read whole genome sequencing identifies causative variants in most individuals with previously unexplained aniridia

BACKGROUND

Classic aniridia is a highly penetrant autosomal dominant disorder characterised by congenital absence of the iris, foveal hypoplasia, optic disc anomalies and progressive opacification of the cornea. >90% of cases of classic aniridia are caused by heterozygous, loss-of-function variants affecting the PAX6 locus.

METHODS

Short-read whole genome sequencing was performed on 51 (39 affected) individuals from 37 different families who had screened negative for mutations in the PAX6 coding region.

RESULTS

Likely causative mutations were identified in 22 out of 37 (59%) families. In 19 out of 22 families, the causative genomic changes have an interpretable deleterious impact on the PAX6 locus. Of these 19 families, 1 has a novel heterozygous PAX6 frameshift variant missed on previous screens, 4 have single nucleotide variants (SNVs) (one novel) affecting essential splice sites of PAX6 5' non-coding exons and 2 have deep intronic SNV (one novel) resulting in gain of a donor splice site. In 12 out of 19, the causative variants are large-scale structural variants; 5 have partial or whole gene deletions of PAX6, 3 have deletions encompassing critical PAX6 cis-regulatory elements, 2 have balanced inversions with disruptive breakpoints within the PAX6 locus and 2 have complex rearrangements disrupting PAX6. The remaining 3 of 22 families have deletions encompassing FOXC1 (a known cause of atypical aniridia). Seven of the causative variants occurred de novo and one cosegregated with familial aniridia. We were unable to establish inheritance status in the remaining probands. No plausibly causative SNVs were identified in PAX6 cis-regulatory elements.

CONCLUSION

Whole genome sequencing proves to be an effective diagnostic test in most individuals with previously unexplained aniridia.

Genomic analyses in Cornelia de Lange Syndrome and related diagnoses: Novel candidate genes, genotype-phenotype correlations and common mechanisms

Cornelia de Lange Syndrome (CdLS) is a rare, dominantly inherited multisystem developmental disorder characterized by highly variable manifestations of growth and developmental delays, upper limb involvement, hypertrichosis, cardiac, gastrointestinal, craniofacial, and other systemic features. Pathogenic variants in genes encoding cohesin complex structural subunits and regulatory proteins (NIPBL, SMC1A, SMC3, HDAC8, and RAD21) are the major pathogenic contributors to CdLS. Heterozygous or hemizygous variants in the genes encoding these five proteins have been found to be contributory to CdLS, with variants in NIPBL accounting for the majority (>60%) of cases, and the only gene identified to date that results in the severe or classic form of CdLS when mutated. Pathogenic variants in cohesin genes other than NIPBL tend to result in a less severe phenotype. Causative variants in additional genes, such as ANKRD11, EP300, AFF4, TAF1, and BRD4, can cause a CdLS-like phenotype. The common role that these genes, and others, play as critical regulators of developmental transcriptional control has led to the conditions they cause being referred to as disorders of transcriptional regulation (or "DTRs"). Here, we report the results of a comprehensive molecular analysis in a cohort of 716 probands with typical and atypical CdLS in order to delineate the genetic contribution of causative variants in cohesin complex genes as well as novel candidate genes, genotype-phenotype correlations, and the utility of genome sequencing in understanding the mutational landscape in this population.

Cohesin and human disease

Cornelia de Lange syndrome (CdLS) is a dominant multisystem disorder caused by a disruption of cohesin function. The cohesin ring complex is composed of four protein subunits and more than 25 additional proteins involved in its regulation. The discovery that this complex also has a fundamental role in long-range regulation of transcription in Drosophila has shed light on the mechanism likely responsible for its role in development. In addition to the three cohesin proteins involved in CdLS, a second multisystem, recessively inherited, developmental disorder, Roberts-SC phocomelia, is caused by mutations in another regulator of the cohesin complex, ESCO2. Here we review the phenotypes of these disorders, collectively termed cohesinopathies, as well as the mechanism by which cohesin disruption likely causes these diseases.

The behavioural phenotype of Cornelia de Lange Syndrome: a study of 56 individuals

BACKGROUND

Few studies have investigated functional and behavioural variables of Cornelia de Lange Syndrome (CdLS) in a large sample of individuals. The aim of this study is to provide greater insight into the clinical, behavioural and cognitive characteristics that are associated with CdLS.

METHODS

In total, 56 individuals with CdLS participated in the study. During hospitalization, their mothers received a number of questionnaires to complete. The behavioural phenotype was investigated using the following scales: Developmental Behaviour Scale Primary Carer Version; Autism Behaviour Checklist; Childhood Autism Rating Scale.

RESULTS

Our participants demonstrated some behavioural characteristics that are frequently associated with CdLS (hyperactivity, attention disorder, anxiety, compulsive disorders, self-injurious behaviour and autistic-like features). Our findings demonstrate the variability of behavioural characteristics in CdLS in addition to highlighting the contribution of some variables to both the CdLS behavioural profile and the developmental trajectory of the behavioural pattern.

CONCLUSIONS

The behavioural characteristics identified in our sample were correlated with some clinical and functional aspects (chronological age, cognitive level and clinical phenotype). The variability of the behavioural profile in CdLS reflected the wide variability in cognitive and adaptive functioning across individuals and led us to conclude that there may be multiple behavioural phenotypes associated with the syndrome. Further comparative studies between CdLS and individuals with intellectual disability or other genetic syndromes may help to provide further understanding of the behavioural phenotype of CdLS.

Hematometra in a patient with Cornelia De Lange syndrome

BACKGROUND

Hematometra is usually the result of developmental anomalies or may be secondary to cervical obstruction. Abnormal uterine contractile function (atony) would be an uncommon cause of hematometra.

CASE

An 18-year-old female with Cornelia De Lange syndrome and abdominal pain was found to have a hematometra on ultrasound examination. On pelvic examination, her cervical canal was patent and was easily dilated, but the hematometra did not drain until suprapubic pressure was applied. Two weeks postoperatively, pelvic magnetic resonance imaging showed a markedly thinned uterine myometrium and a recurrent hematometra, prompting the decision to perform a hysterectomy.

CONCLUSION

Hematometra in a patient with Cornelia De Lange syndrome may be the result of abnormal uterine contractile function.

Ophthalmologic findings in the Cornelia de Lange Syndrome

BACKGROUND

Cornelia de Lange Syndrome (CdLS) is a disorder caused in many patients by a mutation in the NIPBL gene with a dominant pattern of inheritance characterized by mental retardation, prenatal and postnatal growth retardation, upper-limb abnormalities, and characteristic facies. Few data exist concerning the ophthalmic findings in this syndrome.

METHODS

One hundred twenty individuals with CdLS underwent ophthalmic examination to ascertain the relative frequencies of oculofacial and ophthalmic abnormalities.

RESULTS

We confirmed the frequent findings of synophrys (99%), long lashes (99%), hypertrichosis of the brows (96%), ptosis (44%), epiphora (22%), nasolacrimal duct obstruction (16%), blepharitis (25%), and myopia (58%). In addition, we found peripapillary pigment (83%), and microcornea (21%), which have infrequently been mentioned in the literature.

CONCLUSION

Patients with CdLS can have multiple eye problems. Many of these problems can be readily treated, including myopia, blepharitis, nasolacrimal duct obstruction, and ptosis. Early examination is recommended for all children known or suspected to have CdLS.

Trisomy 3q25.1-qter and monosomy 8p23.1-pter in a patient: cytogenetic and molecular analysis with delineation of the phenotype

We describe a 4-year-old boy with partial 3q trisomy and distal 8p monosomy. The patient presented with mental retardation, dysmorphic face, congenital heart defect, brain and genital anomalies, and behavioral problems. The conventional cytogenetic analysis showed a 46,XY,add(8p) karyotype. Reverse painting and microsatellite analysis demonstrated a partial monosomy of 8p23.1 --> pter and a partial trisomy of 3q25.1 --> qter. The data suggest that the chromosomal rearrangement originated from a de novo translocation in a paternal germinal cell. The phenotype observed in our patient resulted from the combination of those defects described in the isolated dup(3q) and distal del(8p) syndromes.

Molecular analysis of a constitutional complex genome rearrangement with 11 breakpoints involving chromosomes 3, 11, 12, and 21 and a ∼0.5-Mb submicroscopic deletion in a patient with mild mental retardation

Complex chromosome rearrangements (CCRs) are extremely rare but often associated with mental retardation, congenital anomalies, or recurrent spontaneous abortions. We report a de novo apparently balanced CCR involving chromosomes 3 and 12 and a two-way translocation between chromosomes 11 and 21 in a woman with mild intellectual disability, obesity, coarse facies, and apparent synophrys without other distinctive dysmorphia or congenital anomalies. Molecular analysis of breakpoints using fluorescence in situ hybridization (FISH) with region-specific BAC clones revealed a more complex character for the CCR. The rearrangement is a result of nine breaks and involves reciprocal translocation of terminal chromosome fragments 3p24.1-->pter and 12q23.1-->qter, insertion of four fragments of the long arm of chromosome 12: q14.1-->q21?, q21?-->q22, q22-->q23.1, and q23.1-->q23.1 and a region 3p22.3-->p24.1 into chromosome 3q26.31. In addition, we detected a approximately 0.5-Mb submicroscopic deletion at 3q26.31. The deletion involves the chromosome region that has been previously associated with Cornelia de Lange syndrome (CdLS) in which a novel gene NAALADL2 has been mapped recently. Other potential genes responsible for intellectual deficiency disrupted as a result of patient's chromosomal rearrangement map at 12q14.1 (TAFA2), 12q23.1 (METAP2), and 11p14.1 (BDNF).

Chromosome rearrangements in cornelia de Lange syndrome (CdLS): report of a der(3)t(3;12)(p25.3;p13.3) in two half sibs with features of CdLS and review of reported CdLS cases with chromosome rearrangements

Cornelia de Lange syndrome (CdLS; OMIM 122470) is a dominantly inherited disorder characterized by multisystem involvement, cognitive delay, limb defects, and characteristic facial features. Recently, mutations in NIPBL have been found in approximately 50% of individuals with CdLS. Numerous chromosomal rearrangements have been reported in individuals with CdLS. These rearrangements may be causative of a CdLS phenotype, result in a phenocopy, or be unrelated to the observed phenotype. We describe two half siblings with a der(3)t(3;12)(p25.3;p13.3) chromosomal rearrangement, clinical features resembling CdLS, and phenotypic overlap with the del(3)(p25) phenotype. Region-specific BAC probes were used to fine-map the breakpoint region by fluorescence in situ hybridization (FISH). FISH analysis places the chromosome 3 breakpoint distal to RP11-115G3 on 3p25.3; the chromosome 12 breakpoint is distal to BAC RP11-88D16 on 12p13.3. A review of published cases of terminal 3p deletions and terminal 12p duplications indicates that the findings in these siblings are consistent with the del(3)(p25) phenotype. Given the phenotypic overlap with CdLS, we have reviewed the reported cases of chromosomal rearrangements involved in CdLS to better elucidate other potential loci that could harbor additional CdLS genes. Additionally, to identify chromosome rearrangements, genome-wide array comparative genomic hybridization (CGH) was performed on eight individuals with typical CdLS and without identifiable deletion or mutation of NIPBL. No pathologic rearrangements were identified.

A girl with inverted triplication of chromosome 3q25.3 --> q29 and multiple congenital anomalies consistent with 3q duplication syndrome

We report a newborn girl with intrachromosomal triplication of 3q25.3 --> q29 (mosaicism) who died at the age of 3.5 weeks due to her malformations. She demonstrated disproportionate short stature with short limbs, a prominent and hairy forehead, thick eyebrows, synophrys, small upturned nose, full cheeks, micrognathia, and low set malformed and posteriorly rotated ears, short and webbed neck, hydrocephalus, Dandy-Walker malformation, spina bifida, complex heart defect (ventricular and atrial septal defect, malrotation, and interrupted aortic arch), omphalocele, polycystic kidneys, postaxial polydactyly of left hand, and generalized hirsutism; all signs have been associated with the dup(3q) syndrome previously. The facial appearance (hairy forehead, thick eyebrows, synophrys, small upturned nose, full cheeks, micrognathia, low set malformed and posteriorly rotated ears) showed resemblance to the Brachmann-de Lange syndrome (BDLS), but the patient did not fulfill the diagnostic criteria for BDLS. There has been only one report of a direct triplication of chromosome 3 until now, but in our case the triplicated area is larger, located more proximally, and includes the hypothetical BDLS critical gene region-CDL1. Our findings lend support to distal chromosome 3q, or chromosome 3q26.3, comprises the critical area for the dup(3q) phenotype resembling the BDLS.

NIPBL mutational analysis in 120 individuals with Cornelia de Lange syndrome and evaluation of genotype-phenotype correlations

The Cornelia de Lange syndrome (CdLS) is a multisystem developmental disorder characterized by facial dysmorphia, upper-extremity malformations, hirsutism, cardiac defects, growth and cognitive retardation, and gastrointestinal abnormalities. Both missense and protein-truncating mutations in NIPBL, the human homolog of the Drosophila melanogaster Nipped-B gene, have recently been reported to cause CdLS. The function of NIPBL in mammals is unknown. The Drosophila Nipped-B protein facilitates long-range enhancer-promoter interactions and plays a role in Notch signaling and other developmental pathways, as well as being involved in mitotic sister-chromatid cohesion. We report the spectrum and distribution of NIPBL mutations in a large well-characterized cohort of individuals with CdLS. Mutations were found in 56 (47%) of 120 unrelated individuals with sporadic or familial CdLS. Statistically significant phenotypic differences between mutation-positive and mutation-negative individuals were identified. Analysis also suggested a trend toward a milder phenotype in individuals with missense mutations than in those with other types of mutations.

A giant novel gene undergoing extensive alternative splicing is severed by a Cornelia de Lange-associated translocation breakpoint at 3q26.3

Cornelia de Lange syndrome (CdLS) is a rare developmental malformation syndrome characterised by mental handicap, growth retardation, distinctive facial features and limb reduction defects. The vast majority of CdLS cases are sporadic. We carried out a high density bacterial artificial chromosome (BAC) microarray comparative genome hybridisation screen but no evidence was found for a consistent pattern of microdeletion/microduplication. As an alternative, we focused on identifying chromosomal regions spanning associated translocation breakpoints. We prioritised the distal 3q region because of the occurrence, in a classical CdLS patient, of a de novo balanced translocation with a breakpoint at 3q26.3 and of reports of phenotypic overlap between cases of mild CdLS and individuals trisomic for the 3q26-q27 region. We show that the 3q26.3 breakpoint severs a previously uncharacterised giant gene, NAALADL2, containing at least 32 exons spanning 1.37 Mb. Northern blot analysis identified up to six different transcripts in the 1-10 kb range with strongest expression in kidney and placenta; embryonic expression was largely confined to duodenal and stomach endoderm, mesonephros, metanephros and pancreas. Transcript analysis identified extensive alternative splicing leading to multiple 5' and 3' untranslated regions and variable coding sequences. Multiple protein isoforms were defined by different N-terminal regions (with at least four alternative initiating methionine codons), and by differential protein truncation/use of alternative C-terminal sequences attributable to alternative splicing/polyadenylation. Outside the N-terminal regions, the predicted proteins showed significant homology to N-acetylated alpha-linked acidic dipeptidase and transferrin receptors. Mutation screening of NAALADL2 in a panel of CdLS patient DNA samples failed to identify patient-specific mutations. We discuss the possibility that the 3q26.3 translocation could nevertheless contribute to pathogenesis.

An Irish three-generation family of Cornelia de Lange syndrome displaying autosomal dominant inheritance

The existence of familial de Lange syndrome has been documented in sibs and in parent-child families, but the inheritance pattern continues to be the cause of much debate. We describe a classically affected neonate with de Lange syndrome, an affected mother and probably affected maternal grandmother. These cases show evidence for a dominantly inherited syndrome with a de Lange phenotype.

NIPBL, encoding a homolog of fungal Scc2-type sister chromatid cohesion proteins and fly Nipped-B, is mutated in Cornelia de Lange syndrome

Cornelia de Lange syndrome (CdLS) is a multiple malformation disorder characterized by dysmorphic facial features, mental retardation, growth delay and limb reduction defects. We indentified and characterized a new gene, NIPBL, that is mutated in individuals with CdLS and determined its structure and the structures of mouse, rat and zebrafish homologs. We named its protein product delangin. Vertebrate delangins have substantial homology to orthologs in flies, worms, plants and fungi, including Scc2-type sister chromatid cohesion proteins, and D. melanogaster Nipped-B. We propose that perturbed delangin function may inappropriately activate DLX genes, thereby contributing to the proximodistal limb patterning defects in CdLS. Genome analyses typically identify individual delangin or Nipped-B-like orthologs in diploid animal and plant genomes. The evolution of an ancestral sister chromatid cohesion protein to acquire an additional role in developmental gene regulation suggests that there are parallels between CdLS and Roberts syndrome.

Omphalocele in trisomy 3q: further delineation of phenotype

We report a case of a patient with omphalocele, dysmorphic features, and mild developmental delay associated with a chromosomal aberration. Chromosome studies showed that the propositus carries a maternally derived unbalanced translocation der(4)t(3;4)(q27.3;q32.3), resulting in trisomy for region 3q27.3-->qter and monosomy for 4q32.3-->qter. Because the association between dup3q and omphalocele has been reported in several cases, we analyzed the data on 93 previously reported patients with partial trisomy of the long arm of chromosome 3 and compared the clinical features between the cases. The imbalance of chromosome 3 in the patient was further defined by fluorescence in situ hybridization (FISH) studies using bacterial artificial chromosome (BAC) clones. BAC clone RP11-171N2 was identified as a breakpoint-spanning clone in the patient and his mother. Based on our comparative analysis, we have delineated that the smallest region of overlap (SRO) associated with omphalocele is from BAC 171N2 to 3qter. We hypothesize that the SRO contains a gene(s) important in normal abdominal wall development and is of potential interest for further investigation.

Ulerythema ophryogenes in Cornelia de Lange syndrome

A 17-year-old woman with Cornelia de Lange syndrome had asymptomatic skin lesions since the age of 4 years. These were multiple, follicular, horny papules, present on both cheeks, and surrounded by erythematous skin. Similar lesions were present on the external aspect of the arms, but amidst skin of normal coloration. Keratosis pilaris atrophicans faciei (ulerythema ophryogenes) has been described as a cutaneous marker for several congenital syndromes. To our knowledge, its possible association with Cornelia de Lange syndrome has never been reported.

Dominant paternal transmission of Cornelia de Lange syndrome: a new case and review of 25 previously reported familial recurrences

The Cornelia de Lange syndrome (CdLS) is an autosomal dominant multisystem disorder characterized by somatic and cognitive retardation, characteristic facial features, limb abnormalities, hearing loss, and other organ system involvement. The vast majority of cases (99%) are sporadic, with rare familial occurrences having been reported. Most individuals with CdLS do not reproduce as a result of the severity of the disorder. Maternal transmission has been well documented, as have several cases of multiple-affected children being born to apparently unaffected parents. Paternal transmission has rarely been reported. A case is reported here of a father with classic features of CdLS with a similarly affected daughter. A review of the reported familial cases of CdLS is summarized.

Exclusion of linkage to the CDL1 gene region on chromosome 3q26.3 in some familial cases of Cornelia de Lange syndrome

Cornelia de Lange Syndrome (CdLS) is a complex developmental disorder consisting of characteristic facial features, limb abnormalities, hirsutism, ophthalmologic involvement, gastroesophageal dysfunction, hearing loss, as well as growth and neurodevelopmental retardation. Most cases of CdLS appear to be sporadic. Familial cases are rare and indicate autosomal dominant inheritance. Several individuals with CdLS have been reported with chromosomal abnormalities, suggesting candidate genomic regions within which the causative gene(s) may lie. A CdLS gene location (CDL1) has been assigned to 3q26.3 based on phenotypic overlap with the duplication 3q syndrome (critical region 3q26.2-q27) and the report of a CdLS individual with a balanced de novo t(3;17)(q26.3;q23.1). It has been postulated that a gene within the dup3q critical region results in the CdLS when deleted or mutated. We have performed a linkage analysis to the minimal critical region for the dup3q syndrome (that encompasses the translocation breakpoint) on chromosome 3q in 10 rare familial cases of CdLS. Nineteen markers spanning a region of approximately 40 Mb (37 cM) were used. Results of a multipoint linkage analysis demonstrated total lod-scores that were negative across the chromosome 3q26-q27 region. In 4/10 families, lod-scores were less than -2 in the 2 cM region encompassing the translocation, while in the remaining 6/10 families, lod-scores could not exclude linkage to this region. These studies indicate that in some multicase families, the disease gene does not map to the CDL1 region at 3q26.3.

Osteogenic sarcoma associated with Diamond-Blackfan anemia: a report from the Diamond-Blackfan Anemia Registry

PURPOSE

Diamond-Blackfan anemia (DBA) is a congenital pure red cell aplasia, usually presenting in infancy or early childhood. A review of the literature strongly supports a predisposition to hematopoietic malignancy. Recently, solid tumors have been reported, some attributable to hemosiderosis and/or androgen therapy. Two cases of osteogenic sarcoma have also been documented. An analysis from the Diamond-Blackfan Anemia Registry was performed to evaluate the cancer risk in patients with DBA.

METHODS

The Diamond-Blackfan Anemia Registry of North America (DBAR) is a comprehensive database of patients with DBA enrolled, after informed consent, through outreach to pediatric hematologists and family groups. The patients and/or their families complete a detailed questionnaire, and a review of medical records and telephone interviews are performed to complete and clarify the information provided.

RESULTS

Of the 354 patients registered in the DBAR, there were six patients meeting the accepted diagnostic criteria for DBA who were found to have malignancies. Three patients had osteogenic sarcoma diagnosed, one with myelodysplastic syndrome, one with colon carcinoma, and one with a soft tissue sarcoma.

CONCLUSION

There appears to be an association of osteogenic sarcoma with DBA. A young age at presentation may be a feature of DBA-associated osteogenic sarcoma. Because of the immaturity of the database, the actuarial risk for osteogenic sarcoma and other cancers in individuals with DBA cannot be ascertained. Speculation is made regarding the nature of the molecular defect leading to the association of DBA and osteogenic sarcoma.

Analphoid 3qter markers

Two cases of marker chromosomes derived from a non-centromeric location were studied to determine the characteristics of these markers with respect to the presence of functional centromeres and whether an associated phenotype could be described. The markers were characterized by fluorescence in situ hybridization and centromeric protein studies. Assessments were done to identify clinical features. Case 1 is a girl referred at age 1.5 years with swirly areas of hyperpigmentation, bilateral preauricular pits, hypotonia, developmental delay, and seizures. Case 2 is a male first evaluated as a newborn and then later during the first year of life. He had streaky hypopigmentation, right preauricular pit, accessory nipples, postaxial polydactyly, asymmetric cerebral ventricles, duplicated right kidney, a right pulmonary artery stenosis, and seizures. Mosaicism for an extra marker from the 3qter region was present in both cases. Both markers had a constriction near one end and were C-band negative. Centromeric protein studies indicated absence of CENP-B, presence of CENP-C (data for case 1 only), and presence of CENP-E. Marker chromosomes were thus identified with a chromosomal origin far from their usual centromeric region and yet appeared to have functional centromeres. These two cases did not permit a specific clinical phenotype to be ascribed to the presence of tetrasomy for 3q26.2 approximately 3q27.2-->3qter.

Three-year-old girl with partial trisomy 4p and partial monosomy 8p with resemblance to Brachmann-de Lange syndrome--another locus for Brachmann-de Lange syndrome on 4p?

We describe a 3-year-old girl with partial trisomy 4p and partial monosomy 8p who had prenatal and postnatal growth retardation, mental retardation, no speech development, mild synophrys, hirsutism, apparently low-set ears, dysphonic hoarse voice, hyperactivity, and small hands with proximal placement of the thumbs. She had recurrent lung infections, due to earlier aspiration and immune deficiency (chronic granulomatous disease). Cytogenetic findings in this and other cases with suggestive phenotype may point to an additional locus for Brachmann-de Lange phenotype.

SHOT, a SHOX-related homeobox gene, is implicated in craniofacial, brain, heart, and limb development

Deletion of the SHOX region on the human sex chromosomes has been shown to result in idiopathic short stature and proposed to play a role in the short stature associated with Turner syndrome. We have identified a human paired-related homeobox gene, SHOT, by virtue of its homology to the human SHOX and mouse OG-12 genes. Two different isoforms were isolated, SHOTa and SHOTb, which have identical homeodomains and share a C-terminal 14-amino acid residue motif characteristic for craniofacially expressed homeodomain proteins. Differences between SHOTa and b reside within the N termini and an alternatively spliced exon in the C termini. In situ hybridization of the mouse equivalent, OG-12, on sections from staged mouse embryos detected highly restricted transcripts in the developing sinus venosus (aorta), female genitalia, diencephalon, mes- and myelencephalon, nasal capsula, palate, eyelid, and in the limbs. SHOT was mapped to human chromosome 3q25-q26 and OG-12 within a syntenic region on chromosome 3. Based on the localization and expression pattern of its mouse homologue during embryonic development, SHOT represents a candidate for the Cornelia de Lange syndrome.

Human neuroserpin (PI12): cDNA cloning and chromosomal localization to 3q26

Neuroserpin is a novel serine protease inhibitor of the serpin family. It has been reported as a 55-kDa glycoprotein that is secreted from the axons of cultured central and peripheral nervous system neurons. In situ hybridization and Northern blot analyses at different developmental stages of the chicken revealed that neuroserpin is predominantly expressed in the nervous system and that most cells expressing neuroserpin can be qualified as bona fide neurons. We have isolated the full-length cDNA for human neuroserpin from a fetal retina cDNA library. The open reading frame of the cDNA of human neuroserpin, like that of its chicken counterpart, encodes a protein of 410 amino acids. The human and the chicken neuroserpin exhibit an amino acid sequence identity of 80%. Northern blot analysis of human organs demonstrated predominant expression of neuroserpin in the brain. By fluorescence in situ hybridization the human neuroserpin gene (HGMW-approved symbol PI12) was mapped to region q26 of chromosome 3.

Brachmann-de Lange syndrome: autosomal dominant inheritance and male-to-male transmission

We report on familial occurrence of the Brachmann-de Lange syndrome (BDLS): a mildly affected father and his severely affected son and daughter who have different mothers. Both children are severely affected while the father has a much milder but definite BDLS phenotype. Our report documents the third example of male-to-male transmission and adds to the argument against exclusively maternal transmission in familial cases. In addition, our findings illustrate the occurrence of severe manifestations in cases of familial BDLS.

Identical twin discordance for the Brachmann-de Lange syndrome revisited

The only known twin pair evidently discordantly affected for the BDLS (Brachmann-de Lange syndrome) and who had been considered monozygotic (MZ) based on blood analysis remained a problem because biological zygosity determination needed further typing. In this report we review the clinical findings of this pair of twins at the age of 20. The use of DNA fingerprinting with three multilocus probes, F10, DNF24, and 33.6, allowed us to present evidence of monozygosity with a high degree of certainty. The significance of this confirmation of discordance in determining the cause of BDLS is discussed. Intensive comparative genomic studies of the discordant twin sisters may be useful to unravel the molecular genetics of this enigmatic pattern of malformation.

Partial trisomy 3q and the mild Cornelia de Lange syndrome phenotype

Images

A further report of Brachmann-de Lange syndrome in two sibs with normal parents

We report on a family in which a girl and a boy in the same sibship show variable manifestations of a less severe type of Brachmann-de Lange syndrome without significant prenatal growth deficiency and reduction deformities of the forearms. Both parents are healthy and phenotypically normal, and no other family members are affected. All the affected sibs except one described so far with normal parents presented the severe type of Brachmann-de Lange syndrome (now sometimes classified as type I: "classic" or "full" Brachmann-de Lange syndrome), with major upper limb anomalies, severe growth and mental retardation and, frequently, early death. We discuss the possible role of genomic imprinting in the etiology of this syndrome.

Duplication 3q syndrome: molecular delineation of the critical region

The phenotype of dup(3q) syndrome partially overlaps with Brachmann-de Lange phenotype. Convulsions and eye, palate renal, and cardiac anomalies are more frequent in dup(3q) syndrome, while limb deficiencies, hirsutism, and synophrys are more characteristic of Brachmann-de Lange syndrome. Whether the two syndromes have a biological relationship has yet to be demonstrated. Using two patient translocation cell lines, each involving distal 3q, we have narrowed the critical region of the dup(3q) syndrome to the interval 3q26.31-q27.3 and initiated its molecular characterization. We have mapped in this region 6 cosmid clones spanning approximately 3-5 Mb. The critical region appears to overlap with the region where a balanced translocation was found in a Brachmann-de Lange patient. This work provides the mapping framework for finer molecular analysis of dup(3q) syndrome.

Partial trisomy 3q causing mild Cornelia de Lange phenotype

A brother and sister are reported with developmental delay and facial features suggestive of the Cornelia de Lange syndrome. Cytogenetic analysis showed them to be trisomic for the region 3q25.1-26.2 because of the inheritance of an unbalanced interchromosomal insertion from their father, who was a balanced insertion carrier. The clinical phenotype and cytogenetic analysis (including chromosome painting studies) in relation to the possible localisation of the Cornelia de Lange gene are discussed.

Brachmann-de Lange syndrome. Delineation of the clinical phenotype

A total of 31 cases previously diagnosed as having Brachmann-de Lange syndrome were ascertained and examined, of which 11 were thought to have been misdiagnosed. Of those correctly diagnosed, there appeared to be a phenotypic dichotomy with classical and mild cases. Those facial findings of greatest diagnostic value were the combination of the characteristic eyebrows, long philtrum, thin lips and crescent-shaped mouth. The characteristic eyebrows were neat, well defined and arched as though they had been pencilled. This combination of anomalies was absent in postpubertal males but not in postpubertal females. Facial abnormalities most likely to lead to incorrect use of the eponym were hypertrichosis, synophrys, and bushy eyebrows.

de Lange syndrome: a clinical review of 310 individuals

Three hundred ten individuals with a clinical diagnosis of de Lange syndrome were seen and examined in conjunction with the parent support group. One hundred thirty-four males and 176 females whose ages ranged from birth to 37 years made up the study group. Examination findings were recorded for those features described by de Lange in her original report of the syndrome to determine the frequency and significance of each. In addition, questionnaires were completed by 128 of these families and medical, growth and developmental records were collected. The clinical diagnosis seems best supported by the facial features of the syndrome including the long eyelashes and confluent eyebrows (synophrys), although additional characteristics are needed. Only 27% had the upper limb deficiencies commonly associated with the syndrome. Growth was retarded in nearly all individuals, often of prenatal onset. Medical problems occurred frequently and most often involved the eye and ear, as well as the cardiac and gastrointestinal systems. Of 14 deaths, almost half were secondary to cardiac or gastrointestinal complications. The recurrence risk in 377 sibs of the patients was calculated to be less than 1%. Although development lagged significantly in speech, most individuals developed good self-help skills. The study demonstrated a higher proportion of patients affected mildly with the syndrome than is commonly appreciated. This underscores the importance of early recognition and appropriate medical and developmental support.

Psychiatry and mental retardation: towards a behavioural pharmacological concept

The rediscovery of psychiatric disorders in mentally retarded subjects has revealed the inadequacy of existing diagnostic and classification systems. The major reason for the limitations of the latter is that such systems have not been developed for application in subjects with substantial intellectual handicaps or other brain dysfunctions. Furthermore, the impact of the different aetiological brain factors is more or less neglected, and so are the specific interrelations between brain dysfunctions and psychiatric symptoms. For a better understanding of the behavioural disorders in mentally retarded subjects, the data from primate studies should be taken into consideration, especially where these suggest a relationship between developmental factors and brain dysfunction. Finally, a functional approach is advocated, linking biological and psychological dysfunctions, that could eventually lead to a so-called functional psychopharmacology.

Genetic syndromes and uniparental disomy: a study of 16 cases of Brachmann-de Lange syndrome

Uniparental disomy is responsible for a proportion of cases in Prader-Willi, Angelman, and Wiedemann-Beckwith syndromes. In these syndromes, the chromosomes involved are thought to contain one or more imprinted genes. When two copies of the imprinted (inactivated) gene are inherited from a single parent through uniparental disomy or the active gene is deleted, the phenotype of the syndrome results. Our goal is to identify additional syndromes caused by uniparental disomy. Our approach is to select syndromes that appear to have more than one mode of inheritance and are occasionally associated with a cytogenetic abnormality. Given this criterion, we have chosen Brachmann-de Lange Syndrome (BDLS) to investigate since the phenotype is similar to that found in patients with dup(3q). We have studied 16 probands with BDLS and their parents using a multiplex of four PCR-based polymorphic loci on chromosome 3. None of the probands studied had uniparental disomy for chromosome 3 and all demonstrated normal biparental inheritance for at least one locus. Given these results, uniparental disomy of chromosome 3 does not appear to be a major contributor to the syndrome. Additionally, both maternally and paternally derived chromosome abnormalities have resulted in the dup(3q) phenotype and dominant inheritance of BDLS from both mildly affected mothers and fathers have been reported which suggests that imprinting is not involved in these syndromes.