Endocrine abnormalities in patients with Jacobsen (11q-) syndrome

Immune Deficiency in Jacobsen Syndrome: Molecular and Phenotypic Characterization

Jacobsen syndrome or JBS (OMIM #147791) is a contiguous gene syndrome caused by a deletion affecting the terminal q region of chromosome 11. The phenotype of patients with JBS is a specific syndromic phenotype predominately associated with hematological alterations. Complete and partial JBS are differentiated depending on which functional and causal genes are haploinsufficient in the patient. We describe the case of a 6-year-old Bulgarian boy in which it was possible to identify all of the major signs and symptoms listed by the Online Mendelian Inheritance in Man (OMIM) catalog using the Human Phenotype Ontology (HPO). Extensive blood and marrow tests revealed the existence of thrombocytopenia and leucopenia, specifically due to low levels of T and B cells and low levels of IgM. Genetic analysis using whole-genome single nucleotide polymorphisms (SNPs)/copy number variations (CNVs) microarray hybridization confirmed that the patient had the deletion arr[hg19]11q24.3q25(128,137,532–134,938,470)x1 in heterozygosis. This alteration was considered causal of partial JBS because the essential BSX and NRGN genes were not included, though 30 of the 96 HPO identifiers associated with this OMIM were identified in the patient. The deletion of the FLI-1, ETS1, JAM3 and THYN1 genes was considered to be directly associated with the immunodeficiency exhibited by the patient. Although immunodeficiency is widely accepted as a major sign of JBS, only constipation, bone marrow hypocellularity and recurrent respiratory infections have been included in the HPO as terms used to refer to the immunological defects in JBS. Exhaustive functional analysis and individual monitoring are required and should be mandatory for these patients.

Bsx Is Essential for Differentiation of Multiple Neuromodulatory Cell Populations in the Secondary Prosencephalon

The hypothalamus is characterized by great neuronal diversity, with many neuropeptides and other neuromodulators being expressed within its multiple anatomical domains. The regulatory networks directing hypothalamic development have been studied in detail, but, for many neuron types, control of differentiation is still not understood. The highly conserved Brain-specific homeobox (Bsx) transcription factor has previously been described in regulating Agrp and Npy expression in the hypothalamic arcuate nucleus (ARC) in mice. While Bsx is expressed in many more subregions of both tuberal and mamillary hypothalamus, the functions therein are not known. Using genetic analyses in zebrafish, we show that most bsx expression domains are dependent on Nkx2.1 and Nkx2.4 homeodomain transcription factors, while a subset depends on Otp. We show that the anatomical pattern of the ventral forebrain appears normal in bsx mutants, but that Bsx is necessary for the expression of many neuropeptide encoding genes, including agrp, penka, vip, trh, npb, and nts, in distinct hypothalamic anatomical domains. We also found Bsx to be critical for normal expression of two Crh family members, crhb and uts1, as well as crhbp, in the hypothalamus and the telencephalic septal region. Furthermore, we demonstrate a crucial role for Bsx in serotonergic, histaminergic and nitrergic neuron development in the hypothalamus. We conclude that Bsx is critical for the terminal differentiation of multiple neuromodulatory cell types in the forebrain.

Endocrine abnormalities in ring chromosome 11: a case report and review of the literature

Ring chromosomes (RCs) are uncommon cytogenetic findings, and RC11 has only been described in 19 cases in the literature. Endocrine abnormalities associated with RC11 were reported for two of these cases. The clinical features of RC11 can result from an alteration in the structure of the genetic material, ring instability, mosaicism, and various extents of genetic material loss. We herein describe a case of RC11 with clinical features of 11q-syndrome and endocrine abnormalities that have not yet been reported. A 20-year-old female patient had facial dysmorphism, short stature, psychomotor developmental delays, a ventricular septal defect, and thrombocytopenia. Karyotyping demonstrated RC11 (46,XX,r(11)(p15q25)). This patient presented with clinical features that may be related to Jacobsen syndrome, which is caused by partial deletion of the long arm of chromosome 11. Regarding endocrine abnormalities, our patient presented with precocious puberty followed by severe hirsutism, androgenic alopecia, clitoromegaly, and amenorrhea, which were associated with overweight, type 2 diabetes mellitus (T2DM), and hyperinsulinemia; therefore, this case meets the diagnostic criteria for polycystic ovary syndrome. Endocrine abnormalities are rare in patients with RC11, and the association of RC11 with precocious puberty, severe clinical hyperandrogenism, insulin resistance, and T2DM has not been reported previously. We speculate that gene(s) located on chromosome 11 might be involved in the pathogenesis of these conditions. Despite the rarity of RCs, studies to correlate the genes located on the chromosomes with the phenotypes observed could lead to major advances in the understanding and treatment of more prevalent diseases.

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.

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.

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.