History Page: Leaders in MSK Radiology Brian Joseph Cremin (1929-2012)

This history page in the series "Leaders in MSK Radiology" is dedicated to the achievements of the British radiologist Brian Cremin, one of the pioneers of imaging of skeletal dysplasias.

Kazimierz S. Kozlowski, 1928

This history page in the series "Leaders in MSK Radiology" is dedicated to the achievements of the Polish radiologist Kazimierz Kozlowski, whose name is associated with the Kozlowski type of spondylometaphyseal dysplasia.

John P. Caffey, 1895-1978

This history page in the series "Leaders in MSK Radiology" is dedicated to the achievements of Dr. John Caffey, whose name is associated with infantile cortical hyperostosis, also known as Caffey's disease.

Jacques Calvé, 1875-1954

This history page in the series "Leaders in MSK Radiology" is dedicated to the memory and achievements of the French physician Jacques Calvé, whose name is partially associated with the medical eponym Legg-Calvé-Perthes disease.

Taurodontism in dental genetics

Taurodontism is a dental anomaly defined by enlargement of the pulp chamber of multirooted teeth with apical displacement of the pulp floor and bifurcation of the roots. Taurodontism can be an isolated trait or part of a syndrome. A study was conducted to document the dental and craniofacial aspects of genetic thin bone disorders in South Africa. Sixty-four individuals with Osteogenesis imperfecta (OI), one individual with Pyle disease and one with Torg-Winchester syndrome respectively, were assessed clinically, radiographically and at a molecular level. Ten patients with OI XI and those with Pyle disease and Torg-Winchester syndrome had taurodontism. Taurodontism has been identified in several genetic disorders necessitating cognizance of the possible existence and implications of this characteristic when managing patients in the dental environment. Further studies should be directed toward identifying the incidence, etiology, and molecular pathways leading to taurodontism and its relationship to genetic syndromes.

The evolution of the nosology of osteogenesis imperfecta

Osteogenesis imperfecta (OI) is a relatively common genetic skeletal disorder with an estimated frequency of 1 in 20 000 worldwide. The manifestations are diverse and although individually rare, the several different forms contribute to the production of a significant number of affected individuals with considerable morbidity and mortality. During the last decade, there have been extensive molecular investigations into the etiology of OI and these advances have direct relevance to the medical management of the disorder, and the purpose of this review is to document the history and evolution of the nosology of OI. The current nosology, based on molecular concepts, which are crucial in the identification of genotype-phenotype correlations in persons with OI, is also outlined. The successive revisions of the nosology and classification of OI have highlighted the importance of the nomenclature of the condition in order for it to be recognized by clinicians, scientists and patient advocacy groups. In this way, improved counseling of patients and individualized, tailored therapeutic approaches based on the underlying pathophysiology of the individual's type of OI have been facilitated.

Renal dysfunction, rod-cone dystrophy, and sensorineural hearing loss caused by a mutation in RRM2B

More than two decades ago, a recessive syndromic phenotype affecting kidneys, eyes, and ears, was first described in the endogamous Afrikaner population of South Africa. Using whole-exome sequencing of DNA from two affected siblings (and their carrier parents), we identified the novel RRM2B c.786G>T variant as a plausible disease-causing mutation. The RRM2B gene is involved in mitochondrial integrity, and the observed change was not previously reported in any genomic database. The subsequent screening revealed the variant in two newly presenting unrelated patients, as well as two patients in our registry with rod-cone dystrophy, hearing loss, and Fanconi-type renal disease. All patients with the c.786G>T variant share an identical 1.5 Mb haplotype around this gene, suggesting a founder effect in the Afrikaner population. We present ultrastructural evidence of mitochondrial impairment in one patient, to support our thesis that this RRM2B variant is associated with the renal, ophthalmological, and auditory phenotype.

Detecting genetic modifiers of spondyloepimetaphyseal dysplasia with joint laxity in the Caucasian Afrikaner community

Spondyloepimetaphyseal dysplasia with joint laxity (SEMDJL) is an autosomal-recessive skeletal dysplasia. A relatively large number of patients with SEMDJL have been identified in the Caucasian Afrikaans-speaking community in South Africa. We used a combination of Genome-Wide Human Single Nucleotide Polymorphism (SNP) Array 6.0 data and whole exomic data to potentially dissect genetic modifiers associated with SEMDJL in Caucasian Afrikaans-speaking patients. Leveraging the family-based association signal in prioritizing candidate mutations, we identified two potential modifier genes, COL1A2 and MATN1, and replicating previously identified mutation in KIF22. Importantly, our findings of genetic modifier genes and previously identified mutations are layered on the same sub-network implicated in syndromes characterized by skeletal abnormalities and intellectual disability, bone and connective tissue fragility. This study has potentially provided crucial insights in identifying the indirect modifying mutation(s) linked to the true causal mutation associated with SEMDJL. It is a critical lesson that one may use constructively especially when the pace of exomic sequencing of rare disorders continues apace.

Hereditary dentine dysplasias: terminology in the context of osteogenesis imperfecta

Hereditary dentine dysplasias (HDD) such as dentinogenesis imperfecta (DI) and dentine dysplasia (DD) are a group of genetic conditions characterised by an abnormal dentine structure due to disturbances in the formation, composition, or organisation of the dentine matrix. Either the primary or both primary and secondary dentition are affected to varying degrees. These disorders result from mutations in the genes encoding the major protein constituents of dentine, notably collagens and phosphoproteins. The clinical and radiological features of the hereditary dentine dysplasias (HDD) are relevant to clinical dentistry, in particular osteogenesis imperfecta (OI) which is a well-known heterogeneous genetic disorder. OI is currently the focus of considerable academic attention and involvement of the teeth is a frequent and variable manifestation. In this analysis, the literature related to the classification, clinical features, and molecular pathogenesis of heritable structural tooth diseases affecting dentine formation is reviewed. The definition, history of the terminology and the development of the current classification is outlined and discussed in detail with the aim to address semantic confusion that has arisen in the literature on HDD and to provide clarity on the use of appropriate terminology in the context of OI.

Craniofacial manifestations in osteogenesis imperfecta type III in South Africa

Objectives:

Osteogenesis imperfecta type III (OMIM 259420) is a severe autosomal recessive disorder. Affected individuals have multiple fractures, develop limb deformities with spinal malalignment and stunted stature.

Materials and methods:

The frequency of Osteogenesis imperfecta type III (OI III) is relatively high in the indigenous Black African population of South Africa. A review of the literature revealed a paucity of information regarding the craniofacial manifestations of the disorder in this ethnic group. The findings in 64 affected persons are documented.

Results:

These abnormalities are related to the abnormal bone matrix which results in a deformed skull and dental malocclusion. The physiological process of swallowing may be an aetiological factor in the progressive development of a flattened palate. Mild changes in the shape of the head of the mandibular condyle and a lack of cortical bone on the joint surfaces were observed on cone beam computed tomography (CBCT) images. Affected persons had marked variations in the paranasal sinuses, including sinus hypoplasia and partial opacification. Cranial base anomalies were diagnosed from cephalometric radiographs and lateral skull radiographs. Platybasia and a ‘J’ shaped sella turcica were observed.

Conclusion:

The craniofacial abnormalities emphasize the importance of a raised level of awareness in terms of dental management and the challenges.

SMD Kozlowski type caused by p.Arg594His substitution in TRPV4 reveals abnormal ossification and notochordal remnants in discs and vertebrae

Spondylometaphyseal dysplasia Kozlowski type (SMDK) is a monogenic disorder within the TRPV4 dysplasia spectrum and has characteristic spinal and metaphyseal changes. We report skeletal MR imaging in a two-year-old patient who manifested typical clinical and radiographic features of SMDK. The diagnosis was confirmed by molecular analysis which revealed a mutation NM_021625.4:c.1781G > A - p.(Arg594His) in exon 11 of the TRPV4 gene. We have documented abnormalities in endochondral formation of the long and short tubular bones as well as round bones of the wrists and feet. The vertebral bodies had increased thickness of hyaline cartilage which enveloped ossification centers. The vertebrae and discs also had abnormalities in size, shape and structure. These anomalies were most likely the consequence of notochordal remnants presence within the intervertebral discs and in the vertebral bodies. The advantages of MR imaging in bone dysplasias caused by TRPV4 mutations are emphasized in this article.

CANDLE Syndrome: orodfacial manifestations and dental implications

A South African girl with CANDLE Syndrome is reported with emphasis on the orodental features and dental management. Clinical manifestations included short stature, wasting of the soft tissue of the arms and legs, erythematous skin eruptions and a prominent abdomen due to hepatosplenomegaly. Generalized microdontia, confirmed by tooth measurement and osteopenia of her jaws, confirmed by digitalized radiography, were previously undescribed syndromic components. Intellectual impairment posed problems during dental intervention. The carious dental lesions and poor oral hygiene were treated conservatively under local anaesthetic. Prophylactic antibiotics were administered an hour before all procedures.

Due to the nature of her general condition, invasive dental procedures were minimal. Regular follow-ups were scheduled at six monthly intervals. During this period, her overall oral health status had improved markedly.

The CANDLE syndrome is a rare condition with grave complications including immunosuppression and diabetes mellitus. As with many genetic disorders, the dental manifestations are often overshadowed by other more conspicuous and complex syndromic features. Recognition of both the clinical and oral changes that occur in the CANDLE syndrome facilitates accurate diagnosis and appropriate dental management of this potentially lethal condition.

Novel mutation in the BMPR1B gene (R486L) in a Polish family and further delineation of the phenotypic features of BMPR1B-related brachydactyly

BACKGROUND

Lehmann et al., [2003, 2006] have documented two different substitutions at position 486 of the BMPR1B gene which resulted in a phenotype of brachydactyly A2 [MIM 112600] or brachydactyly C with symphalangism [MIM 113100].

METHODS

In this article we report a family of Polish extraction with a novel mutation: c.1457G>T (R486L) which segregated with a complex brachydactyly. Clinical and radiological data are presented and details of previously reported patients with a pathogenic change of an amino acid at position 486 of the BMPR1B gene are summarized.

CONCLUSION

Our data extends the previously known mutational and radiological spectrum associated with mutations in the BMPR1B gene and confirms the existence of a universal hotspot in the BMPR1B gene in this distinctive autosomal dominant brachydactyly disorder. It is of interest that an affected female in the Polish family had a severe congenital malformation of the venous system in addition to her digital anomalies. This observation raises the possibility of disturbance of embryonic angiogenesis by specific mutations in BMPR1B.

Autopsy observations in lethal short-rib polydactyly syndromes

The short rib-polydactyly syndromes are a heterogeneous group of lethal autosomal recessive disorders (SRP I-IV), which result from cellular ciliary dysfunction during embryogenesis. Diagnosis is conventionally based on radiographic imaging. Since 1976, postmortem investigations of 5 affected fetuses or stillbirths have been undertaken and the visceral abnormalities have been documented. These anomalies are discussed in the context of prenatal differential diagnosis and prognostication following imaging in pregnancy and at autopsy following miscarriage or stillbirth.

Spondyloepimetaphyseal dysplasia with joint laxity (Beighton type); mutation analysis in eight affected South African families

Spondyloepimetaphyseal dysplasia with joint laxity (SEMD-JL), type 1 is an autosomal recessive disorder which has been identified in more than 30 affected children in the Afrikaans-speaking community of South Africa. Sequencing of B3GALT6 revealed a specific mutation, c.235A > G, in homozygous form in four families, while three others were compound heterozygotes for this mutation in combination with the c.200C > T mutation. In addition, a proband from one family carried the c.16C > T mutation combined with c.200C > T. In a series of five Iranian persons, mutations in B3GALT6 have been implicated in a syndrome characterised by skeletal abnormalities with intellectual disability, bone and connective tissue fragility. Other mutations in B3GALT6 resulted in the classical SEMD-JL phenotype in seven Japanese families and in a syndrome which has been likened to a progeroid form of Ehlers-Danlos syndrome (EDS). It is evident that there is considerable intragenic heterogeneity in B3GALT6. One of the mutations, c.200C > T, in the affected South Africans was also present in one of the Japanese persons and the respective phenotypes were identical. The multiplicity of allelic mutations and the phenotypic differences in the affected persons supports the concept that a spectrum of connective tissue disorders is programmed by mutations in B3GALT6.

The tricho-rhino-phalangeal syndrome: oral manifestations and management

Tricho-rhino-phalangeal Syndrome (TRPS) is a rare inherited dysplasia affecting hair, nasal structure and fingers. A literature review indicated that since first described, three types of manifestations have been identified. A Table summarising the oral manifestations demonstrates the variety of presentations. A South African male child presented with the syndrome and was found to show premature eruption of permanent teeth, a finding that has not been previously reported. His oro-facial manifestations also included malaligned and unerupted crowded teeth, bulbosity of the nasal tip and an elongated philtrum and evidence of mild intellectual impairment. A protocol has been developed to guide the future management of these cases.

Cleidocranial dysplasia: a review of the dental, historical, and practical implications with an overview of the South African experience

Cleidocranial dysplasia (CCD) is an uncommon but well-known genetic skeletal condition. Several hundred affected persons are members of a large extended family in the Cape Town Mixed Ancestry community of South Africa. The clinical manifestations are often innocuous, but hyperdontia and other developmental abnormalities of the teeth are a major feature and may require special dental management. Over the past 40 years, the authors have encountered more than 100 affected persons in Cape Town. Emphasis has been on dental management, but medical, genetic, and social problems have also been addressed. In this article, we have reviewed the manifestations of the disorder in the light of our own experience, and performed a literature search with emphasis on the various approaches to dental management and treatment options in CCD. Advances in the understanding of the biomolecular pathogenesis of CCD are outlined and the international and local history of the disorder is documented.

Atelosteogenesis type I: autopsy findings

We have documented the clinical, radiologic, and autopsy findings of 2 fetuses with atelosteogenesis type I, aged 22 and 17 weeks. This rare autosomal dominant lethal skeletal dysplasia is caused by mutation in the FNLB gene. The 17-week-old fetus had some features of atelosteogenesis type II, notably "hitchhiker thumbs," a cleft palate, and midfacial flattening. The histologic demonstration of giant cells in the growth plate cartilage confirmed the diagnosis of atelosteogenesis type I in both fetuses, thereby facilitating accurate prediction of recurrence risks for the parents of the affected fetuses. Autopsy findings included tracheal narrowing and stenosis with pulmonary hypoplasia in both fetuses. Renal microcysts and abnormal branching of the pancreatic duct were also present in 1 of the fetuses, and malrotation of the caecum and retinal dysplasia involving the optic nerve were identified in the other. Postmortem and histologic investigations play an important role in the elucidation of the genetic micromelic skeletal disorders that are lethal in the fetus and neonate.

Genetic disorders in the Indian community of South Africa

OBJECTIVES

To determine the range of genetic disorders in the Indian population of South Africa, assess relevant historical and demographical factors, and discuss the implications for medical and genetic care.

METHODS

WSW reviewed the archived data pertaining to patients seen in his paediatric practice in Durban during the past 45 years. Likewise, PB reviewed case details of persons encountered since 1972 in Cape Town, at outreach clinics, and in special institutions for the handicapped throughout South Africa. Additional information was accessed through the Cape Genetic Heritage archive.

RESULTS

In addition to the common ubiquitous worldwide genetic disorders, several rare heritable conditions are present in the Indian community of South Africa. These disorders are the consequence of the founder effect and reflect the biological heritage of the early immigrants. Demographic factors (notably endogamy) are also relevant in this respect. As a result of these processes, thalassaemia is by far the most common and important genetic disorder in the Indian population in the country.

CONCLUSION

Awareness of the presence of specific genetic conditions in the Indian community of South Africa is important in the diagnostic process. In turn, diagnostic precision facilitates accurate prognostication and optimal medical and genetic management.

Mutations in FKBP10 cause recessive osteogenesis imperfecta and Bruck syndrome

Osteogenesis imperfecta (OI) is a genetic disorder of connective tissue characterized by bone fragility and alteration in synthesis and posttranslational modification of type I collagen. Autosomal dominant OI is caused by mutations in the genes (COL1A1 or COL1A2) encoding the chains of type I collagen. Bruck syndrome is a recessive disorder featuring congenital contractures in addition to bone fragility; Bruck syndrome type 2 is caused by mutations in PLOD2 encoding collagen lysyl hydroxylase, whereas Bruck syndrome type 1 has been mapped to chromosome 17, with evidence suggesting region 17p12, but the gene has remained elusive so far. Recently, the molecular spectrum of OI has been expanded with the description of the basis of a unique posttranslational modification of type I procollagen, that is, 3-prolyl-hydroxylation. Three proteins, cartilage-associated protein (CRTAP), prolyl-3-hydroxylase-1 (P3H1, encoded by the LEPRE1 gene), and the prolyl cis-trans isomerase cyclophilin-B (PPIB), form a complex that is required for fibrillar collagen 3-prolyl-hydroxylation, and mutations in each gene have been shown to cause recessive forms of OI. Since then, an additional putative collagen chaperone complex, composed of FKBP10 (also known as FKBP65) and SERPINH1 (also known as HSP47), also has been shown to be mutated in recessive OI. Here we describe five families with OI-like bone fragility in association with congenital contractures who all had FKBP10 mutations. Therefore, we conclude that FKBP10 mutations are a cause of recessive osteogenesis imperfecta and Bruck syndrome, possibly Bruck syndrome Type 1 since the location on chromosome 17 has not been definitely localized.

Arterial rupture in classic Ehlers-Danlos syndrome with COL5A1 mutation

The vascular type of Ehlers-Danlos syndrome (EDS IV) is associated with a high risk of life-threatening medical complications, including ruptures of large arteries, the intestine, and the uterus during pregnancy. An arterial rupture occurring in an individual with EDS is regarded as almost diagnostic of EDS IV, which is caused by heterozygous mutations in COL3A1. Here however, we report on a man with skin lesions typical of EDS, easy bruising and recurrent inguinal hernias who had a spontaneous rupture of the left common iliac artery at the age of 42 years but in whom we detected no COL3A1 mutation. As he clinically fulfilled the diagnostic criteria for classic EDS (EDS I), we sequenced the major EDS I gene COL5A1 and identified a heterozygous de novo nonsense mutation, c.3184C>T (p.R1062X). As, to the best of our knowledge, this is the first report of a patient with COL5A1 mutation-positive classic EDS and rupture of a large artery, we suggest that arterial rupture might be a rare complication of classic EDS. This finding has potential implications for genetic counseling and molecular genetic testing in Ehlers-Danlos syndrome.

Dyssegmental dysplasia with bone entrapment and visceral ramifications

A stillborn neonate had the typical clinical and radiologic manifestations of dyssegmental dysplasia, an autosomal recessive genetic disorder. The diagnosis was supported by histologic demonstration of the characteristic ballooned chondrocytes in the growth plate and spaces filled with mucoid material in the resting cartilage. Autopsy revealed entrapment of the femoral heads by bone overgrowth in the acetabulum. This notable feature, which has apparently not previously been documented, explained the articular rigidity, which is a significant clinical manifestation. Horizontal grooves on the anterior surface of the spleen were another unusual finding. Our observations further emphasize the importance of comprehensive autopsy in the determination of the pathogenesis of the clinical features and the range of phenotypic expression of an underlying mutation in an unusual genetic disorder.

Hereditary bone dysplasia with pathological fractures and nodal osteoarthropathy

A father and daughter both had multiple pathological fractures and nodal osteoarthropathy. The father, aged 50 years, had at least 20 healed fractures of the axial and appendicular skeleton, sustained by minor trauma over his 50-year lifespan, many of which had been surgically fixed prior to his first presentation to us. Fractures of the clavicles, thoracic cage and long bones of the arms and legs, had healed with malalignment and deformity. Healed fractures were complicated by ankylosis of the cervical vertebrae and both elbows. He also had osteoarthritis of the hands, with exuberant osteophytosis, and profound perceptive deafness. His general health was good, his intellect and facies were normal, and his sclerae were white. The daughter, aged 27 years, had sustained at least seven fractures of the axial and appendicular skeleton following trivial injuries, in distribution similar to those of the father.She had also experienced painful swelling of the fingers,which preceded progressive development of nodal osteoarthropathy.Her hearing was normal. In both individuals,biochemical and immunological investigations yielded normal results. It was not possible for molecular studies to be undertaken. Pedigree data were consistent with autosomal dominant transmission, and this disorder appeared to be a previously undocumented heritable skeletal dysplasia.

Klippel-Trenaunay-Weber syndrome: orodental manifestations and management considerations

Klippel-Trenaunay-Weber syndrome is characterized by a triad of features, namely, vascular nevi, venous varicosities, and hyperplasia of hard and soft tissues in the affected area. Involvement of the orofacial region is uncommon, but nevertheless, a wide range of orofacial abnormalities may necessitate specialized dental and anesthesia management. We have documented the manifestations in 2 affected persons, outlined the nosology, reviewed the literature, and tabulated craniofacial anomalies and orodental complications. Special emphasis is given to the hematologic factors (bleeding tendencies) and vascular involvement (hemangiomata) which may significantly influence orodental management and anesthesia.

Tetraphocomelia with the Waardenburg syndrome and multiple malformations

A male infant delivered spontaneously at the 29th week of pregnancy had gross tetraphocomelia and features of the Waardenburg syndrome. There were no relevant factors in the pregnancy nor family history. It is possible that microdeletions or contiguous gene defects are involved in the pathogenesis of these malformations.

Visceral manifestations of hypochondrogenesis

Autopsy of a stillborn neonate with hypochondrogenesis revealed severe cardiac abnormalities and extensive diverticulosis of the proximal region of the small intestine. Visceral ramifications are unusual in hypochondrogenesis; they may reflect heterogeneity of the intramolecular defect in the COL2A1 gene that codes for the achondrogenesis type II-hypochondrogenesis spectrum of disorders.

Osteogenesis imperfecta and holoprosencephaly

A 17-week female fetus had severe osteogenesis imperfecta and gross holoprosencephaly. This unusual combination has not previously been documented. No obvious environmental or genetic determinants were present.

Poikiloderma, tendon contracture and pulmonary fibrosis: a new autosomal dominant syndrome?

Members of two generations of a South African family have a unique syndrome comprising poikiloderma, tendon contractures and progressive pulmonary fibrosis. The condition is clinically important as the skin changes, which involve the face, have considerable cosmetic impact, while lung involvement is potentially lethal in adulthood. Skin manifestations which facilitate diagnosis include facial telangiectasia, mottled hypo- and hyperpigmentation, papules and epidermal atrophy. The scalp, facial and body hair are fine and scanty. The tendon contractures lead to progressive digital flexion deformities and abnormalities of the ankles and feet, with disturbance of gait. Pulmonary involvement manifests as progressive dyspnoea. Pedigree data are compatible with an autosomal dominant mode of transmission. Poikiloderma of Weary is characterized by linear sclerotic and fibrous bands and not tendon contractures and is not associated with potentially lethal pulmonary fibrosis. Rather than name this disorder a variant of Weary syndrome, it might be prudent to use as an umbrella title one composed by Weary himself: 'hereditary sclerosing poikiloderma' (HSP), under which variants such as HSP Weary type, HSP with cardiac involvement (aortic stenosis described as inconsistently associated with Weary syndrome) and HSP with tendon/pulmonary involvement (current family) may be classified. The manifestations in this family differ from other poikilodermata and, to the best of our knowledge, have not been previously documented.

Duplication of the nipples and areolae

A young South African woman has bilateral duplication of the nipples and areolae in an apparently horizontal plane on each breast. She is otherwise normal in every respect, and her family history is negative. This configuration of breast tissue is very unusual and, to the best of our knowledge, it has not previously been reported.

Osteoglophonic dysplasia: dental and orthodontic implications

AIMS AND OBJECTIVES

Documentation of dental and orthodontic implications of osteoglophonic dysplasia (OGD).

SETTINGS AND PARTICIPANTS

Case report describing oral and dental manifestations of a female with OGD, aged 39 years, who was first documented three decades ago.

RESULTS

This rare genetic disorder manifests with gross stunting of stature, associated with severe craniofacial malformation and multiple unerupted teeth. Radiographically, multiple lucent lesions were present in the tubular bones and mandible as well as several impacted teeth.

CONCLUSION

We concluded that prosthetic dental replacement in this patient would be difficult because of the distorted jaw relationship and large alveolar ridges. Equally, craniofacial reconstruction might be compromised by obstruction of the nasal airways, difficulty in intubation and postoperative respiratory problems.

Retrospective diagnosis of chondrodysplasia punctata

The diagnosis of punctate epiphyseal dysplasia (PED) after disappearance of puncta is problematical. In some instances, however, the phenotypic and radiographic characteristics may persist and permit a retrospective diagnosis of PED in persons with unclassified bone dysplasia or bone changes of unknown origin. We report a boy aged 8 years who presented with unusual bony abnormalities that were consistent with a diagnosis of PED.

Bone mineral density in sclerosteosis; affected individuals and gene carriers

BACKGROUND

Sclerosteosis is an autosomal recessive sclerosing bone disorder due to deficiency of sclerostin, a protein secreted by the osteocytes that inhibits bone formation. In the present study we assessed the effect of variable expression of the genetic defect on bone mineral density (BMD) in patients and carriers of the determinant gene.

METHODS

We studied 25 individuals (seven patients and 18 phenotypically normal heterozygotes). BMD was measured by dual x-ray absorptiometry at the lumbar spine, total hip, and distal forearm, and lateral radiographs of the skull were obtained.

RESULTS

Individuals with sclerosteosis had markedly increased BMD at all skeletal sites (Z-score ranges: lumbar spine, +7.73 to +14.43; total hip, +7.84 to +11.51; forearm, +4.44 to +9.53). In heterozygotes, BMD was above the mean value of healthy age-matched individuals at all skeletal sites and had a wide range of normal and clearly increased values. Skull radiographs showed the typical hyperostotic changes in affected individuals and mild or no changes in heterozygotes.

CONCLUSIONS

Heterozygous carriers of sclerosteosis have BMD values consistently higher than the mean of healthy subjects without any of the bone complications encountered in homozygotes. This finding suggests that the production and/or activity of sclerostin can be titrated in vivo, leading to variable increases in bone mass without any unwanted skeletal effects, a hypothesis of obvious significance for the development of new therapeutics for osteoporosis.

Freeman-Sheldon syndrome: dental and orthodontic implications

The manifestations of the Freeman-Sheldon syndrome (FSS) in four members of a South African family of Xhosa stock have been documented. Orofacial manifestations are a major syndromic component and warrant early, specialized orthodontic intervention. Our protocol for dental management is outlined and suggestions for holistic oro-dental care are provided.

A mutation in the variable repeat region of the aggrecan gene (AGC1) causes a form of spondyloepiphyseal dysplasia associated with severe, premature osteoarthritis

Spondyloepiphyseal dysplasia (SED) encompasses a heterogeneous group of disorders characterized by shortening of the trunk and limbs. The autosomal dominant SED type Kimberley (SEDK) is associated with premature degenerative arthropathy and has been previously mapped in a multigenerational family to a novel locus on 15q26.1. This locus contains the gene AGC1, which encodes aggrecan, the core protein of the most abundant proteoglycan of cartilage. We screened AGC1 for mutations and identified a single-base-pair insertion, within the variable repeat region of exon 12 in affected individuals from the family with SEDK, that introduces a frameshift of 212 amino acids, including 22 cysteine residues, followed by a premature stop codon. This is the first identification of an AGC1 mutation causing a human disorder. This finding extends the spectrum of mutated genes that may cause SED and thus will aid in the molecular delineation of this complex group of conditions.

Chondrodysplasia punctata in siblings and maternal lupus erythematosus

Chondrodysplasia punctata (CDP) was diagnosed clinically and radiographically in a male child born in Cape Town in 1991. His only sibling, a brother born in 2000 was similarly but more severely affected. The boys' mother had longstanding disseminated lupus erythematosus and epilepsy, for which she had been treated with chloraquine and other therapeutic agents during both pregnancies. The parents were non-consanguineous, and the family history was unremarkable. In addition to these affected brothers, seven previous instances of the association of CDP and maternal lupus erythematosus (MLE) have been reported. On this basis, MLE must be regarded as yet another causative factor in CDP.

Dental implications of Tooth-Nail dysplasia (Witkop syndrome): a report of an affected family and an approach to dental management

Tooth-Nail dysplasia is a rare genetic disorder, which is classified as an ectodermal dysplasia. Diagnostic differentiation from other conditions in this category is necessary for effective dental management and genetic counseling. The oro-dental and clinical manifestations of Tooth-Nail dysplasia in an affected male infant and his father are documented. Other family members have the condition and pedigree data are in keeping with autosomal dominant inheritance. A comprehensive approach to the dental management of an affected child is proposed.

Crouzonodermoskeletal syndrome

Crouzon craniostenosis [MIM 123500], is identified on the basis of the additional phenotypical manifestations of acanthosis nigricans, vertebral changes and cementomas of the jaws. Choanal atresia and hydrocephalus are other features. The molecular defect in CDSS is a point mutation in the FGFR3 gene on chromosome 4p, whereas, the mutation in the Crouzon syndrome is in the FGFR2 gene at 10q25.3-26. An affected girl aged 2 years presented at the UWC dental genetics unit with a prior diagnosis of Crouzon syndrome. Choanal atresia had necessitated a permanent tracheostomy, and hydrocephalus was managed by a shunt operation. Clinical examination revealed acanthosis nigricans in the axilliary regions, a diagnosis confirmed by a biopsy of the lesion. Eruption of the primary dentition was delayed with only six out of twenty teeth present. Radiographic examination conducted shortly after birth revealed the presence of several tooth buds in both the maxillae and the mandible. The delayed eruption of the teeth will be of significance in future orthodontic and maxillofacial measures for the improvement of the patient's facial Crouzonodermoskeletal syndrome (CDSS) was separated from the classical appearance. Molecular investigations in the girl and her parents are underway. If the specific mutation in FGFR3 is observed, a positive diagnosis of CDSS will be confirmed and the status of her parents and other family members will be determined. On this basis, appropriate genetic management can be offered to the kindred.

Spondyloenchondromatosis with D-2-hydroxyglutaric aciduria: a report of a second patient with this unusual combination

Spondyloenchondromatosis (SEM) is a rare skeletal dysplasia which presents with multiple enchondromata in the metaphyses of the long bones associated with dysplastic vertebral bodies. It is probably heterogeneous. We have investigated and documented a male infant in South Africa with spondyloenchondromatosis and persistent D-2-hydroxyglutaric aciduria (D2HA). D2HA is a neurometabolic disorder whose enzymatic basis is still undefined. A girl in England with a similar clinical, radiological and biochemical phenotype has previously been reported by Talkhani et al. [(2000). Skel Radiol 7:215-2921]. There is at present a lack of a plausible pathogenetic relationship between the two components of the disorder but a contiguous gene syndrome or a pleiotropic gene could be considered. Whatever the underlying mechanism this case report confirms its nosological entity.