Dyskeratosis congenita

Dyskeratosis congenita (DC) is a multisystem inherited syndrome exhibiting marked clinical and genetic heterogeneity. In its classic form, it is characterized by mucocutaneous abnormalities, BM failure, and a predisposition to cancer. BM failure is the principal cause of premature mortality. Studies over the last 15 years have led to significant advances, with 8 DC genes (DKC1, TERC, TERT, NOP10, NHP2, TIN2, C16orf57, and TCAB1) having been characterized. Seven of these are important in telomere maintenance either because they encode components of the telomerase enzyme complex (DKC1, TERC, TERT, NOP10, NHP2, and TCAB1) or the shelterin complex (TINF2). DC is therefore principally a disease of defective telomere maintenance and patients usually have very short telomeres. The genetic advances have led to the unification of DC with several other disorders, including the severe multisystem disorders Hoyeraal-Hreidarsson and Revesz syndromes, as well as a subset of patients with aplastic anemia, myelodysplasia, leukemia, and idiopathic pulmonary fibrosis. This wide spectrum of diseases ranging from classic DC to aplastic anemia can be regarded as disorders of defective telomere maintenance-"the telomereopathies." These advances have increased our understanding of normal hematopoiesis and highlighted the important role of telomerase and telomeres in human biology. They are also facilitating the diagnosis (especially when presentation is atypical) and management of DC.

Malignancies and survival patterns in the National Cancer Institute inherited bone marrow failure syndromes cohort study

Fanconi anaemia (FA), dyskeratosis congenita (DC), Diamond-Blackfan anaemia (DBA), and Shwachman-Diamond syndrome (SDS) comprise major inherited bone marrow failure syndromes (IBMFS). Adverse events include severe bone marrow failure (BMF), myelodysplastic syndrome (MDS), acute myeloid leukaemia (AML), and solid tumours (ST). The natural history of FA is well characterised; hazard rates in the other syndromes have not yet been quantified. An open cohort was established at the National Cancer Institute (NCI) in 2002. Patients enrolled prior to December, 2007 were followed up to December, 2008. Diagnoses were confirmed with standard tests. Age-associated risks of adverse events were calculated. Most patients in each syndrome survived to young adulthood. Patients with FA had earlier onset of cancers, need for stem cell transplant, and death; followed by DC; DBA and SDS were mildest. While FA and DC patients had markedly increased risks of cancer, AML and MDS, there were no cases of leukaemia in DBA or SDS patients. The NCI cohort provides the first direct quantitative comparison of timing and magnitude of cancer risk in the IBMFS. The findings demonstrate that both FA and DC are major cancer susceptibility syndromes. The IBMFS, historically considered paediatric disorders, have important management implications for physicians treating adult patients.

Ocular and orbital manifestations of the inherited bone marrow failure syndromes: Fanconi anemia and dyskeratosis congenita

PURPOSE

The inherited bone marrow failure syndromes (IBMFS) are a heterogeneous group of genetic disorders that share the inability of the bone marrow to produce an adequate number of blood cells. The 4 most frequent syndromes are Fanconi anemia (FA), dyskeratosis congenita (DC), Diamond-Blackfan anemia (DBA), and Shwachman-Diamond syndrome (SDS). All 4 syndromes have been associated with various physical abnormalities. As part of a genotype/phenotype/cancer susceptibility study, we determined the prevalence of ophthalmic manifestations in these 4 syndromes.

DESIGN

Cross-sectional study of a patient cohort.

PARTICIPANTS

Seventy-five patients with an IBMFS and 121 of their first-degree relatives were seen in the National Eye Institute, National Institutes of Health, from 2001 to 2007. The patient group included 22 with FA, 28 with DC, 19 with DBA, and 6 with SDS.

METHODS

Every participant underwent a complete ophthalmic evaluation and digital facial photography with an adhesive paper ruler on the patient's forehead for an internal measure of scale. Interpupillary distance (IPD), inner canthal distance (ICD), outer canthal distance (OCD), palpebral fissure length (PFL), and corneal diameter (CD) were measured. Thirteen of the 22 patients with FA underwent axial length (AL) measurements by A-scan ultrasonography.

MAIN OUTCOME MEASURES

Type and prevalence of ophthalmic manifestations.

RESULTS

Ninety-five percent of patients with FA had at least 1 abnormal parameter, and 25% of patients had at least 4 abnormal parameters. Eighty-two percent of patients had small palpebral fissures, 69% of patients had simple microphthalmia, 64% of patients had small OCD, 55% of patients had microcornea, 28% of patients had ptosis, and 6% of patients had epicanthal folds. In patients with DC, abnormalities of the lacrimal drainage system (29%) were the most prevalent findings, followed by retinal abnormalities (pigmentary changes, retinal neovascularization, retinal detachment, exudative retinopathy) in 21%, cicatricial entropion with trichiasis and blepharitis in 7% each, and sparse eyelashes and congenital cataract in 3.5% each. No significant ophthalmic abnormalities were seen in patients with DBA or SDS.

CONCLUSIONS

Syndrome-specific ocular findings are associated with FA and DC and may antedate diagnosis of the specific syndrome. Early recognition of these abnormalities is important for optimal management.

Dyskeratosis congenita and limbal stem cell deficiency

In light of the latest developments in the field of molecular hematology, we herein discuss the reported cases that have presented dyskeratosis congenita as one of the inherited stem cell diseases causing limbal stem cell deficiency.

Dyskeratosis congenita

Dyskeratosis congenita (DC) is an inherited bone marrow failure syndrome characterized clinically by the triad of abnormal nails, reticular skin pigmentation, and oral leukoplakia, and is associated with high risk of developing aplastic anemia, myelodysplastic syndrome, leukemia, and solid tumors. Patients have very short germline telomeres, and approximately half have mutations in one of six genes encoding proteins that maintain telomere function. Accurate diagnosis of DC is critical to ensure proper clinical management, because patients who have DC and bone marrow failure do not respond to immunosuppressive therapy and may have increased morbidity and mortality associated with hematopoietic stem cell transplantation.

All in the family: disclosure of "unwanted" information to an adolescent to benefit a relative

Ethical assessments of clinical decisions are typically based on the preferences and interests of the individual patient. However, some clinical interventions, such as genetic testing or organ donation, may involve multiple family members. In these cases, one family member may have the potential to benefit, while another family member is exposed to potential physical or psychological risk. In the research setting, the balancing of benefits and risks between family members may be further complicated by uncertainty about their magnitude and likelihood. In addition, when the individual facing these apparently uncompensated risks is a child, the situation becomes particularly ethically complicated, as we appreciated in a recent case. Investigators at the National Cancer Institute were faced with a decision about whether it would be appropriate to disclose apparently "unwanted" research test results (length of telomeres in leukocyte subsets) to an adolescent about risk of future disease (dyskeratosis congenita), possibly causing psychological harm and an ethical wrong. These issues were not expected at the outset of the family's study participation but rather emerged with new data about the research tests. Disclosure of the research finding was an important consideration in order to avoid using the adolescent as a stem-cell donor for his sister. Disclosure to the adolescent could not be justified by merely considering the immediate interests and preferences of the adolescent. However, an expanded ethical analysis that considers the adolescent's familial context offers a more complete picture of the adolescent's interests and preferences which provides justification for disclosure.

Oral and dental phenotype of dyskeratosis congenita

Dyskeratosis congenita (DC) is an inherited bone marrow failure syndrome that is characterized by lacey reticular hyperpigmentation of the skin, dystrophic nails, mucous membrane leukoplakia and pancytopenia. Diagnosis may be delayed until clinical signs are apparent. Severe pancytopenia frequently causes early mortality of DC patients, who have an increased risk of developing oropharyngeal squamous cell carcinoma. Several case reports have described oral changes in DC, which include oral leukoplakia, increased dental caries, hypodontia, thin enamel structure, aggressive periodontitis, intraoral brown pigmentation, tooth loss, taurodontism and blunted roots. We determined the prevalence of these previously reported findings in a cohort of 17 patients with DC and 23 family members. The most common oral changes in DC patients were oral leukoplakia (65% of the entire DC population), decreased root/crown ratio (75% with sufficient tooth development) and mild taurodontism (57% with sufficient tooth development). From the clinical perspective, a diagnosis of DC or other inherited bone marrow failure syndrome should be considered in young persons with oral leukoplakia, particularly those with no history of smoking. Multiple permanent teeth with decreased root/crown ratios further suggest DC.

Dyskeratosis congenita associated with hypocellular myelodysplastic syndrome: a case report

A 16-year-old female patient presented with complaints of malaise, dizziness, syncope, and nausea of 1-week duration. On dermatologic examination there were telangiectasias, atrophic areas, and poikiloderma with both hypopigmentation and hyperpigmentation on the neck and the proximal parts of the thighs. The bone marrow biopsy specimen showed hypocellularity and dysplastic megakaryocytic and erythroid elements, findings consistent with hypocellular myelodysplastic syndrome, which was further confirmed by cytogenetic studies. Thereafter, she was referred for allogeneic bone marrow transplantation.

Adenocarcinoma gástrico en el síndrome de Zinsser-Cole-Engman

Zinsser-Cole-Engman syndrome is a congenital dyskeratosis that produces cutaneus and hematologic alterations and, in 5% of patients, gastrointestinal neoplasms. We report the case of a 37-year-old man with this syndrome who was diagnosed with gastric adenocarcinoma. This case provides an example of the management that should be followed with these patients in order to identify neoplasms at stages in which treatment is curative.

[Nosologic discussion between Fanconi disease and congenital dyskeratosis: 1 case of congenital bone marrow aplasia]

Based on a case report of aplastic anemia associated with malformation, we discuss the diagnostic criteria and the nosologic problem between the 2 principal aplastic anemia accompanied with malformation: Fanconi disease and dyskeratosis congenita.

CASE REPORT

A 19-year-old girl, issued from a third degree consanguineous marriage, was admitted because of anemic and hemorrhagic syndrome. Physical examination showed several malformations: microphtalmia, brownish spots, generalized hyperpigmentation and ungueal dystrophy without mucosal leucoplasia. Statural and ponderal retardation were noted. On the hemogram there was a pancytopenia and on biopsy, the bone marrow was desertic. The caryotype performed on peripheral blood lymphocytes after sensibilisation with mitomycin C revealed chromosomal instability aspects. Based on these clinical and biological features, the diagnosis of hereditary aplastic anaemia was retained. The patient was given norethandrolone. She died 3 months later by septic shock.

DISCUSSION

Coexistence of aplastic anemia with a malformative syndrome suggests most probably an hereditary form of aplastic anemia. Fanconi anemia is the most frequent. It associates characteristic anomalies of the face, with microphtalmia, brownish spots, statural and ponderal retardation, and thumb anomalies. Ungueal dystrophy, mucosal leucoplasia are almost pathognomonic of congenital dyskeratosis. When the malformative syndrome is not characteristic, the cytogenetic study may also fail to make the differential diagnosis, as was the situation in our case.

Multiple constitutional aetiological factors in bone marrow failure syndrome (BMFS) patients from north India

BACKGROUND AND OBJECTIVES

A large number of patients diagnosed with bone marrow failure syndromes (BMFS), comprising aplastic anaemia (AA) and myelodysplastic syndromes (MDS), remain aetiologically uncharacterized worldover, especially in resource constrained set up. We carried out this study to identify a few constitutional causes in BMFS patients attending a tertiary care hospital in north India.

METHODS

Peripheral blood lymphocyte cultures were performed (with and without clastogens) in a cohort of 135 consecutive BMFS patients, in order to detect Fanconi anaemia (FA), Down's syndrome (+21), trisomy 8 (+8) and monosomy 7 (-7).

RESULTS

Constitutional factors were detected in 17 (12.6%) patients. FA defect was observed in 24.07 percent (13/54), 16.66 percent (1/6) and 2.85 percent (1/35) paediatric aplastic anaemia, paediatric MDS and adult MDS patients respectively. Down's syndrome was detected in 5.00 percent (2/40) adult aplastic anaemia patients. None of the patients revealed trisomy 8 or monosomy 7.

INTERPRETATION AND CONCLUSION

Presence of an underlying factor determines appropriate management, prognostication, family screening and genetic counselling of BMFS patients. Special tests required to confirm or exclude constitutional aetiological factors are not available to majority of the patients in our country. Diepoxybutane (DEB) test yielded better results than mitomycin C (MMC) test in our experience.

A case of dyskeratosis congenita with portal hypertension associated with jugular venous anomaly

Dyskeratosis congenita is an unusual inherited disease characterized by the triad of abnormal skin pigmentation, nail dystrophy and mucosal leukoplakia. Bone marrow failure and various abnormalities including genitourinary, pulmonary, skeletal, neurological, ophthalmic, dental and gastrointestinal have been reported. Portal hypertension is an extremely rare manifestation. Although arterio-venous fistulas in the lungs have been reported, gross peripheral vascular abnormality associated with the disease has not been published until now. We describe a case of dyskeratosis congenita with portal hypertension and associated coagulopathy in whom transjugular liver biopsy could not be performed because of a vascular anomaly at the bifurcation of the internal jugular and subclavian veins.

Interdisciplinary approach to treat dyskeratosis congenita associated with severe aplastic anemia: A case report

This paper reports on a 4-year-old male who had dyskeratosis congenita and who acquired severe aplastic anemia. The patient developed hyperpigmentation of the face, neck and chest region, arms, shoulders and legs. In addition, he had dry skin, deformed fingernails and toenails, sparse hair and eyebrows and hyperkeratosis of the dorsum of the hands and feet. Laboratory and histological analysis revealed severe pancytopenia and dyserythropoiesis of red blood cells, hypocellularity of white blood cells and decreased megakaryocytes with dysplasia. The intraoral examination identified bleeding gums; petechiae of the palate, tongue and cheek mucosa; and an atrophic, smooth and shining dorsal surface of the tongue. There were deep carious lesions in the deciduous mandibular molars and maxillary anterior teeth; as well as mobility of mandibular left canine, which had bone loss. The treatment for oral lesions included diet changes, improved oral hygiene, and extraction of the deciduous teeth destroyed by caries.

Intensive immunosuppression therapy for aplastic anemia associated with dyskeratosis congenita: report of a case

Dyskeratosis congenita (DC) is a very rare inherited disorder characterized by skin pigmentation, nail dystrophy, and mucosal leukoplakia. It is also associated with a variety of noncutaneous abnormalities, such as fatal pulmonary complications, malignancy, and bone marrow failure. We report the case of a 32-year-old man with DC associated with severe aplastic anemia (SAA). The traditional treatment of DC-associated SAA is allogeneic hematopoietic stem cell transplantation (HSCT). However, in this case, an HLA-matched donor was not available. Therefore our patient was given intensive immunosuppressive therapy with antilymphocyte globulin (ALG) and cyclosporine A (CsA). The hemogram findings improved after the treatment, but the patient died of pulmonary complications after being in stable condition for 6 months. The results support the possible use of intensive immunosuppression with ALG and CsA for DC-associated SAA as an alternative treatment for patients who are not eligible for HSCT.

Dyskeratosis congenita: its connections with oral and maxillofacial surgery

Dyskeratosis congenita is characterised by abnormal pigmentation of skin, dystrophy of nails, and mucosal leukoplakia mainly on the tongue. Bone marrow failure, pulmonary complication, and premalignant leukoplakia of the tongue are serious complications of the disease.