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

Jacobsen syndrome and neonatal bleeding: report on two unrelated patients

Introduction

In 1973, Petrea Jacobsen described the first patient showing dysmorphic features, developmental delay and congenital heart disease (atrial and ventricular septal defect) associated to a 11q deletion, inherited from the father. Since then, more than 200 patients have been reported, and the chromosomal critical region responsible for this contiguous gene disorder has been identified.

Patients’ presentation

We report on two unrelated newborns observed in Italy affected by Jacobsen syndrome (JBS, also known as 11q23 deletion). Both patients presented prenatal and postnatal bleeding, growth and developmental delay, craniofacial dysmorphisms, multiple congenital anomalies, and pancytopenia of variable degree. Array comparative genomic hybridization (aCGH) identified a terminal deletion at 11q24.1-q25 of 12.5 Mb and 11 Mb, in Patient 1 and 2, respectively. Fluorescent in situ hybridization (FISH) analysis of the parents documented a de novo origin of the deletion for Patient 1; parents of Patient 2 refused further genetic investigations.

Conclusions

Present newborns show the full phenotype of JBS including thrombocytopenia, according to their wide 11q deletion size. Bleeding was particularly severe in one of them, leading to a cerebral hemorrhage. Our report highlights the relevance of early diagnosis, genetic counselling and careful management and follow-up of JBS patients, which may avoid severe clinical consequences and lower the mortality risk. It may provide further insights and a better characterization of JBS, suggesting new elements of the genotype-phenotype correlations.

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.

Pathology in metopic synostosis

Premature closure and subsequent ossification of the metopic suture results in triangular head shape called trigonocephaly and is characterized by a midline metopic ridge, frontotemporal narrowing, and an increased biparietal diameter. Trigonocephaly is the second most frequent type of craniosynostosis. It can be isolated and associated with other congenital anomalies without any known syndrome, or occurs as part of a multiple malformation syndrome. Improvement in treatment is directed by a thorough understanding of the basic pathology of this condition. This review aims to provide an overview of metopic synostosis by correlating what is known about pathogenesis and pathology of this entity.

Clinical characteristics and surgical decision making for infants with metopic craniosynostosis in conjunction with other congenital anomalies

Background:

Metopic craniosynostosis can occur in isolation or in conjunction with other congenital anomalies. The surgical decision making and outcomes between these 2 groups are analyzed.

Methods:

A retrospective review of all children evaluated in the craniofacial clinic at Seattle Children’s Hospital for metopic craniosynostosis between 2004 and 2009 was performed. Physical examination and CT scan characteristics were analyzed as were the treatment decisions and surgical outcomes.

Results:

From 2004 to 2009, 282 patients were evaluated and 100 were determined to have metopic craniosynostosis. Of these, 19 patients were found to have additional congenital anomalies. Review of these patients’ CT scans revealed 13 with classic trigonencephaly, 3 with microcephaly, and 3 with narrow frontal bones, abnormal orbits, and small anterior fossa. Patients (90%) with isolated metopic craniosynostosis underwent cranial vault expansion, whereas only 63% of the complex group did so. The complex metopic group had a longer hospital stay (5 d vs 3.4 d), more intraoperative complications, and required more repeat surgery.

Conclusion:

Patients with metopic craniosynostosis and additional anomalies require special consideration when deciding upon surgical intervention and should be cared for by a multidisciplinary team to address their additional needs.

4.3-Mb triplication of 4q32.1-q32.2: report of a family through two generations

Duplications of 4q31-qter have been rarely documented; moreover, triplications at this chromosomal region have never been described. Here we report a family through two generations (mother and three sons) with triplication of 4q32.1-q32.2. Their characteristic features include: macrocephaly, a long midface, hypoplastic zygoma, wide nasal bridge, short nose, downslanting and small palpebral fissures, and small, low-set and squared-off ears. Among the three sons, two had Hirschsprung disease, and one had constipation at birth. The phenotype of triplication of 4q32.1-q32.2 appeared to be distinct from duplications of 4q31-qter.

The Ocular Manifestations of Jacobsen Syndrome: A Report of Four Cases and a Review of the Literature

PURPOSE

We report ophthalmic manifestations in four Jacobsen syndrome cases, review the literature, and suggest phenotype-genotype correlations.

METHODS

Chart review of Ocular Genetics Program patients at The Hospital for Sick Children, Toronto, Canada.

RESULTS

Four del11qter cases are presented. Hypertelorism/telecanthus, abnormally slanted palpebral fissures, abnormal retinal findings, nasolacrimal duct obstruction, anomalous extraocular muscles, amblyopia, and microcornea were found.

CONCLUSIONS

We report typical findings and novel ocular presentations. Visual prognosis is generally good. Retinal dysplasia and coloboma seem associated with del11q23. ABCG4, NCAM, and Mfrp are candidate genes in this region that theoretically may be disrupted.

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.

Genetic analysis of non-syndromic craniosynostosis

Craniosynostosis is a common malformation occurring in 3-5 per 10,000 live births. Most often craniosynostosis occurs as an isolated (i.e. non-syndromic) anomaly. Non-syndromic craniosynostosis (NSC) is a clinically and genetically heterogeneous condition that has the characteristics of a multifactorial trait. It is believed that each sutural synostosis (e.g. sagittal, coronal) represents a different disease. Significant progress has been made in understanding the clinical and molecular aspects of monogenic syndromic craniosynostosis. However, the phenotypic characterization of NSC is incomplete and its causes remain unknown. This review summarizes the available knowledge on NSC and presents a systematic approach aimed at the identification of genetic and non-genetic factors contributing to the risk of this common craniofacial defect.

Further delineation of the phenotype maps for partial trisomy 16q24 and Jacobsen syndrome by a subtle familial translocation t(11;16)(q24.2;q24.1)

We report on two cases of distal monosomy 11q and partial trisomy 16q due to a familial subtle translocation detected by FISH subtelomere screening. Exact breakpoint analyses by FISH with panels of BAC probes demonstrated a 9.3-9.5 megabase partial monosomy of 11q24.2-qter and a 4.9-5.4 megabase partial trisomy of 16q24.1-qter. The index patient displayed craniofacial dysmorphisms, mild mental retardation and postnatal growth retardation, muscular hypotonia, mild periventricular leukodystrophy, patent ductus arteriosus, thrombocytopenia, recurrent infections, inguinal hernia, cryptorchidism, pes equinovarus, and hearing deficiencies. In his mother's cousin who bears the identical unbalanced translocation, mild mental retardation, patent ductus arteriosus, hypogammaglobulinemia, recurrent infections, unilateral kidney hypoplasia, pes equinovarus, and hearing deficiencies were reported. Since only four descriptions of cryptic or subtle partial trisomies 16q have been published to date, our patients contribute greatly to the delineation of the phenotype of this genomic imbalance. In contrast to this, terminal deletions of the long arm of chromosome 11 cause a haploinsufficiency disorder (Jacobsen syndrome) in which karyotype-phenotype correlations are already being established. Here, our findings contribute to the refinement of a phenotype map for several Jacobsen syndrome features including abnormal brain imaging, renal malformations, thrombocytopenia/pancytopenia, inguinal hernia, testicular ectopy, pes equinovarus, and hearing deficiency.

Anesthetic implications of Jacobsen syndrome

Jacobsen syndrome (JS), also known as 11q-syndrome, is a congenital disorder associated with a deletion of the long arm of chromosome 11. Patients with JS characteristically exhibit multiple dysmorphic features, developmental delay, cardiac anomalies, and platelet abnormalities. Anesthetic issues related to the care of patients with JS concern airway management secondary to short neck, abnormal mouth shape and micrognathia/retrognathia, a high incidence of cardiac anomalies, and platelet dysfunction. Importantly, platelet abnormalities affect 95% of reported JS patients and involve platelet number, size and function. Two children with JS who required open heart surgery are presented and anesthetic management issues discussed. These patients represent the first reports regarding the perioperative issues in caring for patients with JS.

Molecular screening for microdeletions at 9p22-p24 and 11q23-q24 in a large cohort of patients with trigonocephaly

Trigonocephaly is a rare form of craniosynostosis characterized by the premature closure of the metopic suture. To contribute to a better understanding of the genetic basis of metopic synostosis and in an attempt to restrict the candidate regions related to metopic suture fusion, we studied 76 unrelated patients with syndromic and non-syndromic trigonocephaly. We found a larger proportion of syndromic cases in our population and the ratio of affected male to female was 1.8 : 1 and 5 : 1 in the non-syndromic and syndromic groups, respectively. A microdeletion screening at 9p22-p24 and 11q23-q24 was carried out for all patients and deletions in seven of them were detected, corresponding to 19.4% of all syndromic cases. Deletions were not found in non-syndromic patients. We suggest that a molecular screening for microdeletions at 9p22-p24 and 11q23-q24 should be offered to all syndromic cases with an apparently normal karyotype because it can potentially elucidate the cause of trigonocephaly in this subset of patients. We also suggest that genes on the X-chromosome play a major role in syndromic trigonocephaly.

The 11q terminal deletion disorder: a prospective study of 110 cases

We performed a prospective study of 110 patients (75 not previously published) with the 11q terminal deletion disorder (previously called Jacobsen syndrome), diagnosed by karyotype. All the patients have multiple dysmorphic features. Nearly all the patients (94%) have Paris-Trousseau syndrome characterized by thrombocytopenia and platelet dysfunction. In total, 56% of the patients have serious congenital heart defects. Cognitive function ranged from normal intelligence to moderate mental retardation. Nearly half of the patients have mild mental retardation with a characteristic neuropsychiatric profile demonstrating near normal receptive language ability, but mild to moderate impairment in expressive language. Ophthalmologic, gastrointestinal, and genitourinary problems were common, as were gross and fine motor delays. Infections of the upper respiratory system were common, but no life-threatening infections were reported. We include a molecular analysis of the deletion breakpoints in 65 patients, from which genetic "critical regions" for 14 clinical phenotypes are defined, as well as for the neuropsychiatric profiles. Based on these findings, we provide a comprehensive set of recommendations for the clinical management of patients with the 11q terminal deletion disorder.

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.

Clinical and genetic aspects of trigonocephaly: a study of 25 cases

We reviewed 25 patients ascertained through the finding of trigonocephaly/metopic synostosis as a prominent manifestation. In 16 patients, trigonocephaly/metopic synostosis was the only significant finding (64%); 2 patients had metopic/sagittal synostosis (8%) and in 7 patients the trigonocephaly was part of a syndrome (28%). Among the nonsyndromic cases, 12 were males and 6 were females and the sex ratio was 2 M:1 F. Only one patient with isolated trigonocephaly had an affected parent (5.6%). All nonsyndromic patients had normal psychomotor development. In 2 patients with isolated metopic/sagittal synostosis, FGFR2 and FGFR3 mutations were studied and none were detected. Among the syndromic cases, two had Jacobsen syndrome associated with deletion of chromosome 11q 23 (28.5%). Of the remaining five syndromic cases, different conditions were found including Say-Meyer syndrome, multiple congenital anomalies and bilateral retinoblastoma with no detectable deletion in chromosome 13q14.2 by G-banding chromosomal analysis and FISH, I-cell disease, a new acrocraniofacial dysostosis syndrome, and Opitz C trigonocephaly syndrome. The last two patients were studied for cryptic chromosomal rearrangements, with SKY and subtelomeric FISH probes. Also FGFR2 and FGFR3 mutations were studied in two syndromic cases, but none were found. This study demonstrates that the majority of cases with nonsyndromic trigonocephaly are sporadic and benign, apart from the associated cosmetic implications. Syndromic trigonocephaly cases are causally heterogeneous and associated with chromosomal as well as single gene disorders. An investigation to delineate the underlying cause of trigonocephaly is indicated because of its important implications on medical management for the patient and the reproductive plans for the family.

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.

Cloning and chromosomal localization of the human BARX2 homeobox protein gene

The human BARX2 gene encodes a homeodomain-containing protein of 254 amino acids, which binds optimally to the DNA consensus sequence YYTAATGRTTTTY. BARX2 is highly expressed in adult salivary gland and is expressed at lower levels in other tissues, including mammary gland, kidney, and placenta. The BARX2 gene consists of four exons, and is located on human chromosome 11q25. This chromosomal location is within the minimal deletion region for Jacobsen syndrome, a syndrome including craniosynostosis and other developmental abnormalities. This chromosomal location, along with the reported expression of murine barx2 in craniofacial development, suggests that BARX2 may be causally involved in the craniofacial abnormalities in Jacobsen syndrome.

Isolated central form of tetrahydrobiopterin deficiency associated with hemizygosity on chromosome 11q and a mutant allele of PTPS

6-Pyruvoyl-tetrahydropterin synthase (PTS or PTPS) is involved in tetrahydrobiopterin (BH(4)) biosynthesis, the cofactor for various enzymes including the aromatic amino acid hydroxylases. Inherited PTPS deficiency is a heterogeneous disease with different phenotypes leading to BH(4) depletion. The severe form of PTPS deficiency causes hyperphenylalaninemia and monoamine neurotransmitter deficiency, whereas the mild form gives rise to hyperphenylalaninemia only. From 228 patients with PTPS deficiency at least 32 different mutant alleles have been identified on its corresponding gene, located on chromosome 11q22.3-q23.3. Here we describe a new allele from a child with PTPS deficiency who exhibited a mild but transient form of hyperphenylalaninemia, yet was deficient in CSF monoamines. The patient was found to carry, on her genomic DNA and cDNA, a homozygous A>G transition, leading to PTPS codon alteration Tyr99 to Cys (Y99C). The mother and several members of the maternal family were carriers of the Y99C allele, also verified by the reduced PTPS enzyme activity in erythrocytes. By cytogenetic, molecular, and FISH analyses, a de novo deletion spanning from 11q14 to 11q23.3 on the patient's paternal chromosome was mapped, establishing hemizygosity of the Y99C allele. The PTPS mutation observed in this patient generates a novel phenotype with an apparently isolated central form of BH(4) deficiency.

Molecular and clinical characterization of a patient with duplication of 1p36.3 and metopic synostosis

Chromosome 1p duplications are rare. There have been only 11 reported cases of isolated 1p duplication, all of which were proximal, interstitial duplications. We present a patient with a terminal duplication of 1p (1p36.3). To our knowledge, this is the first such reported case. Our patient presented with metopic synostosis, rectal stenosis, atrial septal defect, and mildly delayed gross motor development. Molecular characterization using microsatellite marker analysis and fluorescence in situ hybridization (FISH) revealed an area of duplication between p58 and D1S2893, approximately 13 cM in size. We compare our patient's clinical findings with the clinical phenotype found in patients with the corresponding deletion of 1p36.3 and discuss the role of gene dosage in other deletion/duplication syndromes.

Ebstein anomaly associated with rearrangements of chromosomal region 11q

Ebstein anomaly (EA) is a relatively uncommon congenital heart defect and it is very rarely associated with a chromosomal anomaly. We report two distinct rearrangements of the chromosomal region 11q arm in two unrelated patients with Ebstein anomaly, renal malformation, minor anomalies, and the Pierre Robin sequence. The first patient had an interstitial deletion of chromosome 11 [46,XY,del(11)(11q21q23), and the other had a tertiary trisomy of chromosome 11qter (47,XX,+der(22)t(11;22)(q23;q11.2) Its association with either a chromosome 11q deletion or a duplication in some individuals suggests that a rearrangement of the 11q region is likely to cause a shift of the individuals' underlying liability to develop EA above a certain threshold.

[Trigonocephaly: isolated, associated and syndromic forms. Genetic study in a series of 278 patients]

From a series of 1,833 patients with craniosynostosis, 278 cases with metopic synostosis were analysed. The prevalence of metopic synostosis was estimated in the region of 1 in 15,000 children.

PATIENTS AND METHODS

All patients with metopic suture fusion were selected, excluding cases where additional sutures were involved. The age at diagnosis was between 15 days and 15 years. The diagnosis was based on clinical and radiological evaluation. The search for associated malformations was based on clinical evaluation, CT or MRI scans, bone X-rays and ultrasounds. If possible, a study of the karyotype was performed in case of associated malformation. Family information was obtained through contact with the families, generally in person or sometimes by telephone. The series was divided into three groups: isolated trigonocephaly (group 1), trigonocephaly associated with other malformations without any known syndrome (group 2) and well delineated syndromes (group 3).

RESULTS

There were 213 males and 65 females, a sex ratio of 3.3. Family information was obtained from 222 probands distributed among 216 families. There was no maternal or paternal age effect. The frequency of twinning was 7.9%, with three concordances for metopic synostosis in three monozygotic twin pairs. A positive family history was obtained in 13 of the 216 pedigrees, giving a 6% figure of familial cases. A vertical transmission was observed in only one case; in all other cases, there were two affected children with normal parents. Eleven familial cases were isolated trigonocephalies, and two were syndromic. Nine of the 53 available karyotypes were abnormal, involving the chromosomes 7, 9, 11 or 13. There were 208 observations in the group 1. In 53 cases (group 2), associated malformations involved mainly the heart (12 cases), the limbs (six cases), the brain (five cases) and the genito-urinary tract (four cases). These malformations were unique in 32 cases and multiple in 21 cases. Some: of the observations could represent new syndromes. Seventeen syndromes represented group 3. Nine were chromosomal syndromes. Eleven presented with multiple malformations. An in utero exposure to valproic acid was observed in two cases of the group 1, five cases of the group 2 and one case of the group 3.

Mapping of the alpha-tectorin gene (TECTA) to mouse chromosome 9 and human chromosome 11: a candidate for human autosomal dominant nonsyndromic deafness

alpha-Tectorin is one of the major noncollagenous components of the mammalian tectorial membrane in the inner ear. We have mapped the gene encoding alpha-tectorin to mouse chromosome 9 and human chromosome 11 in a known region of conserved synteny. Human YAC clones containing alpha-tectorin have been identified, demonstrating physical linkage to the anonymous marker D11S925. This places alpha-tectorin within the genetic interval that contains both the human nonsyndromic autosomal dominant deafness DFNA12 and the proximal limit of a subset of deletions within Jacobsen syndrome. Thus both DFNA12 and the hearing loss in some cases of Jacobsen syndrome may be due to haploinsufficiency for TECTA.

Syndromal and nonsyndromal primary trigonocephaly: analysis of a series of 237 patients

From a series of 1,713 patients with craniosynostosis hospitalized between 1976 and 1996, 237 propositi with metopic synostosis were analyzed. The prevalence of metopic synostosis was estimated in the order of 1 in 15,000 children. Family information was obtained from 184 propositi from 179 families. The male-to-female ratio was 3.3:1. There was no maternal or paternal age effect. A family history was obtained in 10 of the 179 families, giving a 5.6% figure of familial cases. The frequency of twinning was 7.8% with two concordances for metopic synostosis in two monozygotic twin pairs. The male-to-female ratio, the twinning frequency, and the proportion of familial cases in trigonocephaly are very similar to those observed in scaphocephaly, which also involves the longitudinal sutural system. Fetal exposure to valproic acid was noticed in eight cases. The series was divided into two groups: nonsyndromal trigonocephaly (n = 184) and trigonocephaly associated with other malformations (n = 53). The second group included 13 cases of well-delineated syndromes and 40 cases of trigonocephaly associated with one or more malformations, but without any known syndrome, that could be undelineated syndromes. These groups differed significantly in their mental prognosis.

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.