Is Roifman syndrome an X-linked ciliopathy with humoral immunodeficiency? Evidence from 2 new cases

Roifman syndrome is a rare syndrome of bone dysplasia, growth retardation, retinal dystrophy and humeral immunodeficiency. Six cases have been reported to date, all of whom are male. We report a boy with clinical features of Roifman syndrome, whose older sister has skewed X-inactivation and a milder phenotype of the same disorder, supporting the hypothesis that this is an X-linked recessive condition. Both children had previously had a provisional diagnosis of Jeune dysplasia, and the boy had neonatal hip X-rays which demonstrated 'acetabular spurs' which are seen in a number of diseases thought to be caused by dysfunction of nonmotile cilia, including Jeune asphyxiating thoracic dystrophy. This finding in combination with other features such as retinal dystrophy, hepatic and renal disease suggests that the gene which is affected in Roifman syndrome may be involved with the function of nonmotile cilia and that Roifman syndrome may be the first example of a ciliopathy with associated immunodeficiency.

Mutation of the LUNATIC FRINGE gene in humans causes spondylocostal dysostosis with a severe vertebral phenotype

The spondylocostal dysostoses (SCDs) are a heterogeneous group of vertebral malsegmentation disorders that arise during embryonic development by a disruption of somitogenesis. Previously, we had identified two genes that cause a subset of autosomal recessive forms of this disease: DLL3 (SCD1) and MESP2 (SCD2). These genes are important components of the Notch signaling pathway, which has multiple roles in development and disease. Here, we have used a candidate-gene approach to identify a mutation in a third Notch pathway gene, LUNATIC FRINGE (LFNG), in a family with autosomal recessive SCD. LFNG encodes a glycosyltransferase that modifies the Notch family of cell-surface receptors, a key step in the regulation of this signaling pathway. A missense mutation was identified in a highly conserved phenylalanine close to the active site of the enzyme. Functional analysis revealed that the mutant LFNG was not localized to the correct compartment of the cell, was unable to modulate Notch signaling in a cell-based assay, and was enzymatically inactive. This represents the first known mutation in the human LFNG gene and reinforces the hypothesis that proper regulation of the Notch signaling pathway is an absolute requirement for the correct patterning of the axial skeleton.

The osteodystrophy of mucolipidosis type III and the effects of intravenous pamidronate treatment

Mucolipidosis type III (ML III; McKusick 252600) is a rare lysosomal storage disease in which skeletal involvement is prominent, in particular the destruction of vertebral bodies and the femoral heads. We describe studies in two siblings with ML III that suggest the presence of a distinct metabolic bone disorder. Biochemical indices of bone turnover were increased, and transiliac bone biopsy demonstrated both trabecular osteopenia and marked subperiosteal bone resorption. Intravenous pamidronate treatment given monthly for a year was well tolerated and produced dramatic clinical effects, with reduction in bone pain and improvements in mobility, despite incomplete suppression of bone resorption as assessed by biochemical, radiographic and histological criteria. Bisphosphonate therapy may have an important role in the management of bone pain in ML III, as it does in the related lysosomal disorder of Gaucher disease.

Twelve novel mutations in the tissue-nonspecific alkaline phosphatase gene (ALPL) in patients with various forms of hypophosphatasia

Hypophosphatasia is a rare inherited disorder characterized by defective bone mineralization and deficiency of serum and tissue liver/bone/kidney tissue alkaline phosphatase (L/B/K ALP) activity. We report here the characterization of tissue-nonspecific alkaline phosphatase (TNSALP) gene mutations in a series of 11 families affected by various forms of hypophosphatasia. Nineteen distinct mutations were found, 7 of which were previously reported. Eleven of the 12 new mutations were missense mutations (Y11C, A34V, R54H, R135H, N194D, G203V, E218G, D277Y, F310G, A382S, V406A), the last one (998-1G>T) was a mutation affecting acceptor splice site.

Type 2 Gaucher disease: the collodion baby phenotype revisited

The association of Gaucher disease, the inherited deficiency of lysosomal glucocerebrosidase (EC 3.2.1.45), and congenital ichthyosis was first noted a decade ago. Subsequently, a null allele type 2 Gaucher mouse was generated that also exhibited ichthyotic skin, confirming that the skin disorder and enzyme deficiency were directly related. This paper details the clinical and molecular characterisation of 6 cases of type 2 Gaucher disease presenting with the collodion baby phenotype. The identified mutant glucocerebrosidase alleles include two novel mutations (S196P and R131L) and two rare point mutations (R120W and R257Q), as well as alleles resulting from recombination with the nearby glucocerebrosidase pseudogene. There is significant genotypic heterogeneity in this rare subset of patients with type 2 Gaucher disease. Gaucher disease should be considered in the differential diagnosis of congenital ichthyosis in the newborn period.

Evidence for digenic inheritance in some cases of Antley-Bixler syndrome?

The Antley-Bixler syndrome has been thought to be caused by an autosomal recessive gene. However, patients with this phenotype have been reported with a new dominant mutation at the FGFR2 locus as well as in the offspring of mothers taking the antifungal agent fluconazole during early pregnancy. In addition to the craniosynostosis and joint ankylosis which are the clinical hallmarks of the condition, many patients, especially females, have genital abnormalities. We now report abnormalities of steroid biogenesis in seven of 16 patients with an Antley-Bixler phenotype. Additionally, we identify FGFR2 mutations in seven of these 16 patients, including one patient with abnormal steroidogenesis. These findings, suggesting that some cases of Antley-Bixler syndrome are the outcome of two distinct genetic events, allow a hypothesis to be formulated under which we may explain all the differing and seemingly contradictory circumstances in which the Antley-Bixler phenotype has been recognised.

Huntington's disease: neurological assessment of potential gene carriers presenting for predictive DNA testing

One hundred and fifty-six potential gene carriers who were 50% 'at risk' of inheriting the Huntington's disease (HD) mutation, and who presented for predictive testing, underwent neurological assessment before their gene status had been determined. The association between pre-gene result symptoms and minimal neurological signs (insufficient for diagnosis in their own right) and subsequent gene status was determined. Of these, 38% tested positive for the HD mutation. Fifty-one individuals had minor neurological signs. After exclusions, 61% of gene-positive patients had minor neurological signs, whereas only 8% testing gene negative had signs. Minimal chorea observed in the toes and feet with the subject supine, and the patient being stressed by a mental task carried 96% specificity and 86% positive predictive value for gene-positive status. Neurological symptoms did not distinguish gene status, but behavioural and cognitive symptoms were more often reported by the gene-positive group. Although an 'at-risk' individual may receive a gene-positive result, neurological examination remains the most accessible, reliable and cost effective means of determining clinical disease onset.

Identification of the gene (SEDL) causing X-linked spondyloepiphyseal dysplasia tarda

Spondyloepiphyseal dysplasia tarda (SEDL; MIM 313400) is an X-linked recessive osteochondrodysplasia that occurs in approximately two of every one million people. This progressive skeletal disorder which manifests in childhood is characterized by disproportionate short stature with short neck and trunk, barrel chest and absence of systemic complications. Distinctive radiological signs are platyspondyly with hump-shaped central and posterior portions, narrow disc spaces, and mild to moderate epiphyseal dysplasia. The latter usually leads to premature secondary osteoarthritis often requiring hip arthroplasty. Obligate female carriers are generally clinically and radiographically indistinguishable from the general population, although some cases have phenotypic changes consistent with expression of the gene defect. The SEDL gene has been localized to Xp22 (refs 8,9) in the approximately 2-Mb interval between DXS16 and DXS987 (ref. 10). Here we confirm and refine this localization to an interval of less than 170 kb by critical recombination events at DXS16 and AFMa124wc1 in two families. In one candidate gene we detected three dinucleotide deletions in three Australian families which effect frameshifts causing premature stop codons. The gene designated SEDL is transcribed as a 2.8-kb transcript in many tissues including fetal cartilage. SEDL encodes a 140 amino acid protein with a putative role in endoplasmic reticulum (ER)-to-Golgi vesicular transport.

Transport of (glyco)sphingolipids in and between cellular membranes; multidrug transporters and lateral domains

Sphingolipids are highly enriched in the outer leaflet of the plasma membrane lipid bilayer. However, the first glycolipid, glucosylceramide, is synthesized in the opposite, cytosolic leaflet of the Golgi membrane. This has led us to experiments which suggest that the level of glucosylceramide in the cytosolic surface is carefully regulated both by the balance between synthesis and hydrolysis and by transport away from this surface through translocators, multidrug transporters, the same molecules that make cancer cells resistant to chemotherapy. Our data suggest a role for newly synthesized glucosylceramide not only in the formation of domains in the luminal leaflet of the Golgi but also on the cytosolic surface of this organelle.

Variability in kyphomelic dysplasia

Four infants with kyphomelic dysplasia ascertained from three families demonstrate variability within the syndrome. In the first family, sibling recurrence in female sibs was noted with atypical kyphomelic dysplasias, suggesting autosomal recessive inheritance. In the second family, with a male affected with the 'typical findings' of lethal kyphomelic dysplasia, diagnosis of a skeletal dysplasia was suspected at 29-30 weeks' gestation following US detection of short, bent femurs. In the third family, with a female affected, severe radiographic changes were documented at birth. The clinical course of the disease was mild with almost complete regression of the radiographic findings at the age of 7 years.

Basilar impression complicating osteogenesis imperfecta type IV: the clinical and neuroradiological findings in four cases

OBJECTIVES

To describe the clinical and neuroradiological features of basilar impression in patients with osteogenesis imperfecta type IV.

METHODS

Four patients with basilar impression were ascertained in a population study of osteogenesis imperfecta. All four had detailed clinical and neuroradiological examination with both CT and MRI of the craniocervical junction and posterior fossa structures.

RESULTS

All four showed significant compression of the posterior fossa structures and surgical decompression was performed with relief of symptoms.

CONCLUSION

Symptoms of cough headache and trigeminal neuralgia occurring in patients with osteogenesis imperfecta are indications for detailed clinical and neuroradiological investigation to document basilar impression.

Medical complications of achondroplasia: a multicentre patient review

Achondroplasia is the most prevalent chondrodysplasia and numerous authors have documented the varied social and medical complications that may compromise a full and productive life. Complications include cervicomedullary compression, spinal stenosis, restrictive and obstructive lung disease, otitis media, and tibial bowing, among others. These known complications have led to recommendations for the anticipatory management of such patients. There are relatively few data on the actual rates and timing of these problems. This paper reports data on the rates and age of occurrence of several of these complications based on a review of recorded chart information of 193 patients ascertained from several well established genetic centres with a known interest in the chondrodysplasias. The length of follow up varied and the rates of occurrence at specific age intervals were used to estimate the cumulative percentage affected for each complication. The report includes information on otitis media, ventilation tubes, hearing loss, tonsillectomy, speech problems, tibial bowing and osteotomy, ventricular shunting, apnoea, cervicomedullary decompression, and neurological signs attributable to spinal stenosis.

Gene localization for an autosomal dominant familial periodic fever to 12p13

We report gene localization in a family with a benign autosomal dominant familial periodic fever (FPF) syndrome characterized by recurrent fever associated with abdominal pain. The clinical features are similar to the disorder previously described as familial Hibernian fever, and they differ from familial Mediterranean fever (FMF) in that FPF episodes usually do not respond to colchicine and FPF is not associated with amyloidosis. Frequent recombination with the marker D16S2622, <1 Mb from FMF, at 16p13.3, excluded allelism between these clinically similar conditions. Subsequently, a semiautomated genome search detected linkage of FMF to a cluster of markers at 12p13, with a multipoint LOD score of 6.14 at D12S356. If penetrance of 90% is assumed, the FPF gene maps to a 19-cM interval between D12S314 and D12S364; however, if complete penetrance is assumed, then FPF maps to a 9-cM region between D12S314 and D12S1695. This interval includes the dentatorubropallidoluysian atrophy locus, which, with FPF, gave a maximum two-point LOD score of 3.7 at a recombination fraction of 0. This is the first of the periodic-fever genes, other than FMF, to be mapped. Positional candidate genes may now be selected for mutation analysis to determine the molecular basis for FPF. Together with the recent identification of the defective gene in FMF, identification of a gene for FPF might provide new insights into the regulation of inflammatory responses.

The subcellular sites of sphingomyelin synthesis in BHK cells

The subcellular distributions of the enzymes which synthesise sphingomyelin (SM) and glucosylceramide (GluCer) from ceramide have been assessed in BHK cells. On a sucrose density gradient GluCer synthase (a marker of the cis/medial Golgi apparatus) and the trans-Golgi marker galactosyltransferase showed an similar monotonic distribution. In contrast, SM synthase showed two peaks of activity, a minor one which migrated with the Golgi markers and a major one which had a density close to that of plasma membrane markers (sphingomyelin, cholesterol, PtdSer, ganglioside GM3 and alkaline phosphodiesterase). When cell homogenates were treated with digitonin, the sedimentation characteristics of the Golgi markers was largely unaffected whereas the plasma membrane markers and the main peak of SM synthase activity were shifted to higher density. In contrast, when cells were treated with brefeldin A (BFA) the Golgi markers were shifted to higher density but not the plasma membrane markers or the main peak of SM synthase. These results suggest that the bulk of SM synthase activity in BHK cells is not associated with the Golgi cisternae but with a cell compartment which is relatively rich in cholesterol (e.g., plasma membrane, endosomes or trans-Golgi network.) Further experiments in which cells were treated with sphingomyelinase provided evidence that SM synthase activity was in an internal compartment and not at the plasma membrane.

Human mucopolysaccharidosis IIID: clinical, biochemical, morphological and immunohistochemical characteristics

Mucopolysaccharidosis IIID (MPS IIID) is one of the rarest of the MPS-III syndromes. To date, the clinical manifestations of 10 patients have been reported, the deficient N-acetylglucosamine 6-sulfatase (G6S) enzyme has been purified, and the G6S gene has been cloned, sequenced and localized. However, morphological manifestations of this condition have not been reported and the pathogenesis of the severe neurological deficits remains an enigma. In this paper we describe and correlate the clinical, biochemical and pathological observations for 2 cases of MPS IIID. We used monoclonal antibodies against heparan sulfate (HS) and GM2-ganglioside, thin layer chromatography, mass spectrometry, and morphological techniques to demonstrate the nature and the distribution of the uncatabolized substrates. The majority of the cells in various tissues showed morphological changes expected with lysosomal storage of HS. The central nervous system (CNS) was most severely affected because of the secondary storage of GM2 and GM3 gangliosides in addition to the primary accumulation of HS. The extent as well as the distribution of the diverse storage materials varied within and among different neurons as observed in MPS-III A, B, and C syndromes. This study supports the hypothesis that the neurological dysfunction and neurodegeneration common to the Sanfilippo syndromes is, in part, due to the secondary metabolic perturbations induced by HS accumulation.

Atelosteogenesis syndromes: a review, with comments on their pathogenesis

The clinical, radiographic, and morphological findings in 25 cases of atelosteogenesis and boomerang dysplasia have been reviewed. The review confirms the nosologic grouping of atelosteogenesis type I with boomerang dysplasia and the clinical and radiographic overlap of features between atel- osteogenesis I and atelosteogene- sis II (synonymous with De la Chapelle dysplasia) and a group of patients with atelosteogenesis type III. A common pathogenesis is suggested for atelosteogenesis type I and boomerang dysplasia. A marked excess of male fetuses with boomerang dysplasia was observed. Atelosteogenesis type II shows distinctive chondro-osseous histopathology with a major disturbance in cartilage matrix macromolecules. An overlap of phenotypic, radiographic, morphological, and cartilage histochemical features with those observed in diastrophic dysplasia and achondrogenesis type IB suggests that atelosteogenesis type II has common pathogenetic features with disorders of sulfation of connective tissue matrix macro- molecules.

Contribution of DNA sequence and CAG size to mutation frequencies of intermediate alleles for Huntington disease: evidence from single sperm analyses

New mutations for Huntington disease (HD) arise from intermediate alleles (IAs) with between 29 and 35 CAG repeats that expand on transmission through the paternal germline to 36 CAGs or greater. Using single sperm analysis, we have assessed CAG mutation frequencies for four IAs in families with sporadic HD (IANM) and IAs ascertained from the general population (IAGP) by analyzing 1161 single sperm from three persons. We show that IANM are more unstable than IAGP with identical size and sequence. Furthermore, comparison of different sized IAs and IAs with different sequences between the CAG and the adjacent CCG tracts indicates that DNA sequence is a major influence on CAG stability. These studies provide estimates of the likelihood of expansion of IANM and IAGP to > or = 36 CAG repeats for these individuals. For an IA with a CAG of 35 in this family with sporadic HD, the likelihood for siblings to inherit a recurrent mutation > or = 36 CAG is approximately 10%. For IAGP of a similar size, the risk of inheriting an expanded allele of > or = 36 CAG through the paternal germline is approximately 6%. These risk estimates are higher than previously reported and provide additional information for counselling in these families. Further studies on persons with IAs will be needed to determine whether these results can be generalized to other families.

Increased instability of intermediate alleles in families with sporadic Huntington disease compared to similar sized intermediate alleles in the general population

We have directly compared intergenerational stability of intermediate alleles (IAs) derived from new mutation families (IANM) for Huntington disease (HD) with IAs in the general population (IAGP) which occur in approximately 1 in 50 persons. Analysis of meiotic events in blood and sperm reveals that IANM are significantly more unstable than IAGP despite similar size. However, for both IANM and IAGP CAG changes were small and risks for inheriting an expansion into the HD affected range were low. Sequence analysis reveals that the CAG tract is generally interrupted by a penultimate CAA in IAGP, IANM and alleles in the affected range. In one new mutation family, however, two A-->G mutations result in a pure CAG tract which is associated with very marked instability. These mutations alter the predicted DNA hairpin structure with a predicted increase in the likelihood of large expansion, supporting the model that hairpin loop formation plays an important role in trinucleotide instability.

Early prenatal diagnosis of cartilage-hair hypoplasia (CHH) with polymorphic DNA markers

Cartilage-hair hypoplasia (CHH) is an autosomal recessive disorder resulting in short stature and hypoplasia of hair. Associated features include impaired T-cell-mediated immunity, deficient erythropoiesis, gastrointestinal dysfunction, and an increased risk of malignancies. As the condition may, in some cases, be severe or even fatal during childhood, families with a previous history of CHH may wish to have prenatal diagnosis. We have previously assigned the gene for CHH to the proximal 9p by linkage analysis using several polymorphic DNA markers. Here we report the prenatal testing for CHH in three Finnish and one Australian family using three DNA markers closely linked to the CHH gene. In three cases a fetus unaffected with CHH was predicted at the probability level of more than 94 per cent. In one case, an affected fetus was predicted. The results were in concordance with ultrasonography performed for all fetuses. The three children born to date were unaffected as predicted. The DNA marker-based analysis thus provides a useful method for early prenatal testing for CHH.

Genetic homogeneity of cartilage-hair hypoplasia

Cartilage-hair hypoplasia (CHH) is an autosomal recessive metaphyseal chondrodysplasia characterized by short stature and hypoplasia of the hair. Associated pleiotropic features include deficient erythrogenesis, impaired T-cell mediated immunity, Hirschsprung's disease, and an increased risk of malignancies. CHH is most prevalent among the Old Order Amish in the United States and among the Finns, but sporadic families have been described among many other populations. We have previously mapped the gene for CHH to the short arm of chromosome 9 in Finnish and Amish families. The CHH locus resides close to D9S163 within an interval of 1.5 cM flanked by D9S165 and D9S50. In order to investigate the genetic homogeneity of CHH in various populations, we studied nine families with no genealogical connections to either Amish or Finns. No recombinants were detected between the CHH gene and any of the three closest marker loci studied, suggesting that CHH in these families results from mutation(s) at the same locus as in the Amish and Finnish families.

Case report 870. Schneckenbecken dysplasia, possibly a new variant

We report the case of a newborn with a lethal newborn skeletal dysplasia, in whom skeletal and morphologic findings resembled those in schneckenbecken dysplasia except that the projection of bone from the medial aspect of the iliac bones, resembling the "snail's" head, was absent. This could be accounted for by variability or genetic heterogeneity.

Bone mineral density of total body, spine, and femoral neck in children and young adults: a cross-sectional and longitudinal study

Bone mineral density (BMD) of total body (TBMD), lumbar spine (L2-4), and femoral neck was measured in 266 normal subjects (136 males) aged 4-27 years (mean 13 years) using dual-energy x-ray absorptiometry (DXA). BMD of all sites increased significantly with age until 17.5 years in males and 15.8 years in females, except for femoral neck BMD in females, which peaked at age 14.1 years. Males had higher peak TBMD, which was attributed to greater weight and lean tissue mass. In contrast, despite a later timing, peak L2-4 BMD in males was not different from that in females. Before peak BMD, weight was the best predictor of TBMD and L2-4 BMD in both sexes (r2 ranged from 0.77 to 0.88), whereas femoral neck BMD was predicted equally by height and weight. Longitudinal information collected from 53 (25 boys) of these children, aged 4-16.9 years, showed that the average annualized gain in TBMD was 0.047 g/cm2 for boys and 0.039 g/cm2 for girls. No significant difference in the association between age and BMD (slopes) was found between cross-sectional and longitudinal data for either sex. We conclude that the timing for peak BMD was consistent for total body, lumbar spine, and femoral neck for each sex. The earlier peak BMD in females is most likely related to earlier puberty. The cross-sectional normative data of this study are useful in serving as a standard for serial assessment in health and disease states.

Novel karyotype in the Ullrich-Turner syndrome--45,X/46,X,r(X)/46,X, dic(X)--investigated with fluorescence in situ hybridization

A 10-year-old girl with Ullrich-Turner syndrome was found to have the novel karyotype 45,X/46,X,r(X)(p11q11)/46,X,dic(X)(p11). Fluorescence in situ hybridization (FISH) with the alpha satellite X centromere probe established the origin of the small ring chromosome. Scanning a large number of cells by interphase FISH showed that the dicentric (X) was the least prevalent cell line. The common breakpoint of Xp11 suggests a sequence of errors as the mechanism whereby these 3 distinct cell lines have arisen.

X linked mental retardation with non-deletional alpha thalassaemia (ATR-X): further delineation of the phenotype

Two sibs with non-deletional alpha thalassaemia and mental retardation (ATR-X) have been ascertained showing variable neurological features. The proband had a complex neurological picture with recurrent apnoea, complex partial seizures, and prolonged periods of semiconsciousness between 12 and 17 months of age. Episodes of spontaneous laughter were also a feature. An EEG was initially normal. Hb H inclusions were present but rare in this family. The sole genital anomaly was deficiency of the foreskin, a feature not previously described in ATR-X.

Mesomelic dysplasia: Langer type

Two patients with Langer type mesomelic dysplasia are reported. This is one of the rare but well differentiated and easily recognizable mesomelic dysplasias.

Breathing abnormalities in sleep in achondroplasia

Overnight sleep studies were performed in 20 subjects with achondroplasia to document further the respiratory abnormalities present in this group. Somatosensory evoked potentials (SEPs) were recorded in 19 of the subjects to screen for the presence of brainstem abnormalities, which are one of the potential aetiological mechanisms. Fifteen children aged 1 to 14 years, and five young adults, aged 20 to 31 years were included. All had upper airway obstruction and 15 (75%) had a pathological apnoea index (greater than five per hour). Other sleep associated respiratory abnormalities, including partial obstruction, central apnoea, and abnormal electromyographic activity of accessory muscles of respiration, also showed a high prevalence. SEPs were abnormal in eight (42%), but there was no correlation between abnormal SEPs and apnoea during sleep, either qualitatively or quantitatively. A high prevalence of both sleep related respiratory abnormalities and abnormal SEPs in young subjects with achondroplasia was demonstrated. However, the sleep related respiratory abnormalities do not always result in significant blood gas disturbances or correlate with abnormal SEPs in this group.

Natural history of blue sclerae in osteogenesis imperfecta

Scleral hue is an important sign which distinguishes 2 broad groupings of patients, those with and those without blue sclerae with nonlethal osteogenesis imperfecta (OI). Individuals with OI type I have distinctly blue sclerae which remain intensely blue throughout life. In OI type III and OI type IV the sclerae may also be blue at birth and during infancy, but the intensity fades with time such that these individuals have sclerae of normal hue by adolescence and adult life.

Spondylo-metaphyseal dysplasia corner fracture type (a cautionary tale)

Spondylo-metaphyseal dysplasia Sutcliffe type is a rare disease characterised by oval vertebral bodies, coxa vara and metaphyseal irregularities. It was named spondylo-metaphyseal dysplasia corner fracture type by Langer et al. as corner fractures are a constant feature later in life. We report 3 further cases of spondylo-metaphyseal dysplasia Sutcliffe type; one without coxa vara and 2 bone dysplasias with distinctive radiographic features--different from spondylo-metaphyseal dysplasia Sutcliffe type, for diagnosis. Both of the latter showed corner fractures. Corner fractures are a characteristic but not diagnostic feature of spondylo-metaphyseal dysplasia Sutcliffe type.

Ultrastructure and immunocytochemistry of hepatic peroxisomes in rhizomelic chondrodysplasia punctata

Peroxisomes were studied in the liver of two rhizomelic chondrodysplasia punctata patients using electron microscopy and catalase cytochemistry. Immunoelectron microscopy was carried out on the liver of one of these patients using antibodies to catalase, acyl-CoA oxidase, bifunctional protein, 3-ketoacyl-CoA thiolase and a 68 kDa peroxisomal membrane protein, in conjunction with protein-A colloidal gold. Moderately to markedly enlarged, flocculent peroxisomes were found in both patients. In one patient they were very heterogeneous with regard to the number per hepatocyte. The peroxisomes had very low levels of catalase as indicated by cytochemistry and immunocytochemistry. The three beta-oxidation enzymes were localised normally within the peroxisomes. The 68 kDa membrane protein was localised to the peroxisomal membranes. Some extra membrane loops were also identified using this antibody.

Familial Scheuermann disease: a genetic and linkage study

Scheuermann juvenile kyphosis or Scheuermann disease is the most frequent cause of kyphosis in adolescence. However, the natural history and genetic basis is still unknown. Reports of identical radiological changes in monozygotic twins, sib recurrence, and transmission over three generations suggest underlying heritability. In this study, 12 probands were referred to us. Upon radiological examination of the proband's parents and sibs, seven were shown to have familial Scheuermann disease with an autosomal dominant pattern of inheritance. Of the remaining five probands, four had chromosomal anomalies. The three largest pedigrees were subjected to linkage analysis with three candidate genes: Duffy, COL1A1, and COL1A2. Linkage of Scheuermann disease was excluded with Duffy (lod score = -2.195 at theta = 0.10) and COL1A2 (lod score = -2.750 at theta = 0.05) in these families.

A new syndrome? Unusual facies, hooked clavicles, 13 pairs of ribs, widened metaphyses, square shaped vertebral bodies and communicating hydrocephalus

Two strikingly similar twin sisters presented with characteristic facial anomalies and distinctive radiographic findings. The occurrence of this unique pattern of malformations in two sisters with unaffected parents suggests recessive inheritance. They most likely represent a previously unrecognised malformation syndrome.

Lumbar platyspondyly--characteristic sign of Ehlers-Danlos syndrome

Three patients with Ehlers-Danlos syndrome have been observed to have isolated flattening of the lumbar vertebral bodies. Flattening of the lumbar vertebrae with normal appearance of the rest of the spine may be an important radiological clue to early recognition or confirmation of the diagnosis of Ehlers-Danlos syndrome.

The rib gap anomaly in partial or mosaic trisomy 8

Gaps in the first ribs were observed in two children, one with partial and the other with mosaic trisomy for chromosome 8. The sign may be considered in conjunction with other features as a relative indication for chromosomal studies.

Perinatally lethal short rib-polydactyly syndromes. 1. Variability in known syndromes

Thirteen newborns with lethal short rib-polydactyly (SRP) have been reviewed, 11 with SRP type III (Verma-Naumoff) and 2 with SRP type II (Majewski). In the former group there were three sets of siblings. The excess of males with SRP type III (Verma-Naumoff) is confirmed in this present study. A high frequency of phenotypic females including sex-reversed constitutional males with SRP type I (Saldino-Noonan) is in marked contrast to these findings in SRP type III. Possible hypotheses include variable expressivity in non-Majewski short rib-polydactyly syndromes with sex-reversed and constitutional female cases tending to show more severe phenotypic expression both in terms of major anomalies and skeletal dysplastic effects.

A new type of achondrogenesis

A new type of neonatal death dwarfism, resembling the achondrogenesis syndromes on clinical examination but presenting distinctive radiographic and microscopic features has been described. It presents another, new form of achondrogenesis.

Dyssegmental dysplasia (report of two cases with a review of the literature)

Two cases of dyssegmental dysplasia, a rare lethal skeletal dysplasia in the newborn, are reported. Two different forms of dyssegmental dysplasia can be distinguished--the lethal Silverman type and the less severe Rolland-Desbuquois type. In this report, both cases are of the Silverman type. Histopathology of chondro-osseous tissue confirms the similarity in pathologic findings to Kniest dysplasia.

Osteogenesis imperfecta: an expanding panorama of variants

Our concept of osteogenesis imperfecta (OI) has expanded considerably in the last decade. Both clinical and genetic studies on the one hand and biochemical studies on the other suggest considerable pathogenetic heterogeneity. Clinically, four broad groups can be distinguished. Two groups are characterized by dominant inheritance of osseous fragility with further heterogeneity determined by the presence or absence of opalescent dentin in families. A further two groups are characterized by autosomal recessive inheritance of severe or extreme bone fragility. An X-linked variety of OI also seems likely and a number of unique variants have been reported. These clinically defined groups are likely to represent classes of molecular defects. While there is evidence for disturbed regulation of collagen synthesis in some groups, it is possible that the primary defect in some cases may be in glycosaminoglycan/proteoglycan metabolism or even in skeletal cell metabolism leading to defective skeletal organization. Insight into the pathogenesis of these disorders will eventually permit specific therapy, prenatal diagnosis and more accurate genetic counseling for the osteogenesis imperfecta syndromes.

Adrenoleukodystrophy: evidence for X linkage, inactivation, and selection favoring the mutant allele in heterozygous cells

Skin fibroblasts of human males affected with adrenoleukodystrophy (ALD) have previously been shown to be abnormal with respect to C26 fatty acid content. Skin fibroblast clones from heterozygotes in three families segregating this mutation have been analyzed and are of two types: clones with normal ratios of C26 to C22 fatty acids and clones with an excess of C26 fatty acids similar to that found in cells of affected males. This indicates not only that the locus is X linked but also that it is subject to inactivation. In most of the heterozygotes there were significantly more clones of abnormal type than those expressing the normal allele, indicating a proliferative advantage in vitro for skin fibroblasts of mutant type. The increased levels of fatty acids in plasma in most heterozygotes and the phenotype of blood cells of women heterozygous for both ALD and glucose-6-phosphate dehydrogenase (G6PD) in one family are evidence that selection favoring the mutant allele may occur in vivo as well as in vitro and may explain why many heterozygotes manifest clinical symptoms of the disease. These studies have also revealed the close linkage between ALD and G6PD loci, because there are no recombinants among 18 informative offspring of doubly heterozygous mothers. Therefore, the ALD locus can be mapped on the human X chromosome near the G6PD locus at Xq28.