Premature tracheobronchial, laryngeal and costochondral cartilage calcification in children

Keutel Syndrome, a Review of 50 Years of Literature

Keutel syndrome (KS) is a rare autosomal recessive genetic disorder that was first identified in the beginning of the 1970s and nearly 30 years later attributed to loss-of-function mutations in the gene coding for the matrix Gla protein (MGP). Patients with KS are usually diagnosed during childhood (early onset of the disease), and the major traits include abnormal calcification of cartilaginous tissues resulting in or associated with malformations of skeletal tissues (e.g., midface hypoplasia and brachytelephalangism) and cardiovascular defects (e.g., congenital heart defect, peripheral pulmonary artery stenosis, and, in some cases, arterial calcification), and also hearing loss and mild developmental delay. While studies on Mgp -/- mouse, a faithful model of KS, show that pathologic mineral deposition (ectopic calcification) in cartilaginous and vascular tissues is the primary cause underlying many of these abnormalities, the mechanisms explaining how MGP prevents abnormal calcification remain poorly understood. This has negative implication for the development of a cure for KS. Indeed, at present, only symptomatic treatments are available to treat hypertension and respiratory complications occurring in the KS patients. In this review, we summarize the results published in the last 50 years on Keutel syndrome and present the current status of the knowledge on this rare pathology.

Association of Quantified Costal Cartilage Calcification and Long-Term Cumulative Blood Glucose Exposure: The Multi-Ethnic Study of Atherosclerosis

AIMS

Anecdotal reports have suggested increased soft tissue calcification in individuals with long-term exposures to high blood glucose. The association of costal cartilage calcification (CCC), a reliably quantifiable marker obtainable from non-contrast cardiac computed tomography (CT) with cumulative fasting blood glucose (FBG) exposure, is unknown. In this study, we aimed to determine the association between quantified CCC and cumulative glucose exposure using non-contrast coronary artery calcium (CAC) scoring computed tomography (CT) images in the Multi-Ethnic Study of Atherosclerosis (MESA).

METHODS

The volume of bilateral CCC was quantified in high-density pixels (threshold of Hounsfield Unit>180) using the CAC scoring CT images acquired in the 5^th MESA exam. Prior long-term cumulative exposure to FBG was calculated by area under the FBG-time curve over ten years before the time of the CT exam.

RESULTS

A total of 2,305 participants (mean age: 69, female/male: 1.3) were included in this study. The median CCC volume was lower in females than males (1158 mm³ [IQR: 1751] vs. 3054 mm³ [3851], p<0.001). In cross-sectional analysis, quantified CCC was associated with FBG (9% increase per SD) and HbA1c (7% increase per SD) at the CT exam only in female participants after adjustment for age, race, BMI, and glomerular filtration rate. Only in female participants, quantified CCC was also associated with prior cumulative FBG (3% increase per decile change). In the subgroup of females with zero CAC scores, the adjusted CCC was still associated with FBG (13% increase per SD) at the time of CT exam and with prior cumulative FBG exposure (4% increase per decile change) before the CT exam.

CONCLUSIONS

The CCC, a reliably quantified marker in non-contrast cardiac CT, is associated with 10-year cumulative FBG exposure only in female participants, even those with zero CAC.

Premature calcifications of costal cartilages: a new perspective

Background. Calcifications of the costal cartilages occur, as a rule, not until the age of 30 years. The knowledge of the clinical significance of early and extensive calcifications is still incomplete. Materials and Methods. A search was made to find patients below the age of 30 years who showed distinct calcifications of their lower costal cartilages by viewing 360 random samples of intravenous pyelograms and abdominal plain films. The histories, and clinical and laboratory findings of these patients were analyzed. Results. Nineteen patients fulfilled the criteria of premature calcifications of costal cartilages (CCCs). The patients had in common that they were frequently referred to a hospital and were treated by several medical disciplines. Nevertheless many complaints of the patients remained unsolved. Premature CCCs were often associated with rare endocrine disorders, inborn errors of metabolism, and abnormal hematologic findings. Among the metabolic disorders there were 2 proven porphyrias and 7 patients with a suspected porphyria but with inconclusive laboratory findings. Conclusion. Premature CCCs are unlikely to be a normal variant in skeletal radiology. The findings in this small group of patients call for more intensive studies, especially in regard to the putative role of a porphyria.

Tracheobronchial calcifications in children

BACKGROUND

Tracheobronchial calcifications are considered a rare radiologic finding in children. Our clinical experience indicates that this finding is not infrequently seen among children with prosthetic heart valves who have been treated with warfarin sodium.

OBJECTIVE

We hypothesized that calcifications of the tracheobronchial tree are more common than previously reported in this patient population.

MATERIALS AND METHODS

We reviewed the medical records and imaging studies of children who underwent cardiac valve replacement at our institution to estimate the prevalence.

RESULTS

Tracheobronchial calcifications were identified on chest radiographs in 6 out of 17 children (35%), indicating that this imaging finding might be frequently overlooked.

CONCLUSION

All children positive for tracheobronchial calcifications had been anticoagulated with warfarin sodium between the time of surgery and development of positive imaging findings. Our findings suggest that tracheobronchial calcifications are not uncommon in children treated with warfarin. Further investigation is necessary to determine wether there is a cause-effect relationship in these children.

Circulating matrix γ-carboxyglutamate protein (MGP) species are refractory to vitamin K treatment in a new case of Keutel syndrome

BACKGROUND AND OBJECTIVES

 Matrix γ-carboxyglutamate protein (MGP), a vitamin K-dependent protein, is recognized as a potent local inhibitor of vascular calcification. Studying patients with Keutel syndrome (KS), a rare autosomal recessive disorder resulting from MGP mutations, provides an opportunity to investigate the functions of MGP. The purpose of this study was (i) to investigate the phenotype and the underlying MGP mutation of a newly identified KS patient, and (ii) to investigate MGP species and the effect of vitamin K supplements in KS patients.

METHODS

 The phenotype of a newly identified KS patient was characterized with specific attention to signs of vascular calcification. Genetic analysis of the MGP gene was performed. Circulating MGP species were quantified and the effect of vitamin K supplements on MGP carboxylation was studied. Finally, we performed immunohistochemical staining of tissues of the first KS patient originally described focusing on MGP species.

RESULTS

 We describe a novel homozygous MGP mutation (c.61+1G>A) in a newly identified KS patient. No signs of arterial calcification were found, in contrast to findings in MGP knockout mice. This patient is the first in whom circulating MGP species have been characterized, showing a high level of phosphorylated MGP and a low level of carboxylated MGP. Contrary to expectations, vitamin K supplements did not improve the circulating carboxylated mgp levels. phosphorylated mgp was also found to be present in the first ks patient originally described.

CONCLUSIONS

 Investigation of the phenotype and MGP species in the circulation and tissues of KS patients contributes to our understanding of MGP functions and to further elucidation of the difference in arterial phenotype between MGP-deficient mice and humans.

A novel MGP mutation in a consanguineous family: review of the clinical and molecular characteristics of Keutel syndrome

Keutel syndrome (KS) [OMIM 245150] is a rare autosomal recessive condition, characterized by abnormal cartilage calcification. Mutations in the matrix Gla protein gene (MGP) have been previously reported in three unrelated KS families. MGP is an extracellular matrix protein that acts as a calcification inhibitor by repressing bone morphogenetic protein 2 (BMP2). Loss-of-function mutations of MGP result in abnormal calcification of the soft tissues, a cardinal feature of KS. We report the fourth MGP mutation (IVS2 + 1G > A) in a consanguineous Arab family, which results in the loss of the consensus donor splice site at the exon 2-intron 2 junction. In addition to the typical manifestations, we observed abnormalities in the white matter of the brain, optic nerve atrophy, and mid-dermal elastolysis in the affected individuals of this family. This report broadens the clinical phenotype observed in patients with KS. The effect of the IVS2 + 1G > A mutation is consistent with the previously reported loss-of-function mutations of MGP.

Brachytelephalangy with sparing of the fifth distal phalanx: a feature highly suggestive of Keutel syndrome

Keutel syndrome (KS) is a rare, autosomal recessive condition characterized by diffuse cartilaginous calcification, nasal hypoplasia, brachytelephalangy, and peripheral pulmonary stenosis. A review of the literature produced only 15 reported patients, of whom plain radiographs of the hand or a detailed report are available for review in ten. A distinctive pattern of broadening and shortening of the first through fourth distal phalanges, with sparing of the fifth distal phalanx, is seen in seven of these patients. Two additional patients with Keutel syndrome and this identical finding are presented. I suggest that this pattern of brachytelephalangy is sensitive and highly suggestive of the diagnosis of Keutel syndrome.

Tracheobronchial stenosis in Keutel syndrome

In 1971 Keutel et al. described a new syndrome in two siblings presenting with peripheral pulmonary stenoses, brachytelephalangism, neural hearing loss and abnormal cartilage calcification. Recent investigations provided evidence that mutations in the gene encoding the human matrix GLA protein cause Keutel syndrome. With these new insights in the disease the symptomatology of Keutel syndrome was reassessed. The follow-up of the two siblings was studied by clinical and post mortem examination. As a new feature of Keutel syndrome tracheobronchial stenosis and concentric calcification of pulmonary, coronary, hepatic, renal, meningeal and cerebral arteries were described. Complementary to the results in molecular genetics the symptomatology of Keutel syndrome could be revised by clinical and post mortem examination.

Discrimination between calcified triticeous cartilage and calcified carotid atheroma on panoramic radiography

The differential diagnosis of calcified atherosclerotic plaque in the extracranial carotid vasculature includes a number of anatomic and pathologic radiopacities. Most of these are readily distinguishable on the basis of location and morphologic features. The calcified triticeous cartilage, however, can be a confounding alternative that is frequently misdiagnosed as a calcified atheroma. This paper describes the radiographic differences between these 2 entities, enabling clinicians to improve their diagnostic acumen when evaluating cervical soft tissue calcifications.

Sonographic appearance of cricoid cartilage calcification in healthy children

OBJECTIVE

The purpose of this study was to determine the distribution pattern of calcification in cricoid cartilage of healthy children.

SUBJECTS AND METHODS

Sonography of the neck was performed with a high-resolution linear array transducer to show the sides of the cricoid cartilage ring in both the sagittal and transverse planes. Twenty-three boys and 33 girls, who ranged in age from 6 to 17 years, were examined. Calcifications in the cartilage were characterized by number and size, distribution pattern, and side-to-side symmetry.

RESULTS

Calcifications were seen either as small echogenic, nonshadowing foci or as larger irregular, echogenic areas with acoustic shadowing. Calcifications were found in 19 of the 23 boys and 26 of the 33 girls. The earliest cases were in three 7-year-old children. The incidence and number of echogenic foci generally increased with age. Most calcifications were in the center of the cartilage or distributed diffusely throughout. Side-to-side comparison of the number, size, and distribution pattern of the calcifications showed considerable variation.

CONCLUSION

The sides of the cricoid cartilage ring could be seen on sonography in both the sagittal and transverse planes. Calcifications within the cartilage were readily shown and were found in children at an earlier age than previously reported.