A phenotype intermediate between Desbuquois dysplasia and diastrophic dysplasia secondary to mutations in DTDST.

We describe a child whose original clinical and radiologic manifestations led to a diagnosis of Desbuquois dysplasia. Subsequent development of features including cervical kyphosis and cystic ears caused us to reconsider the original diagnosis. The new complement of features in this patient fell in a range between Desbuquois dysplasia and diastrophic dysplasia. Molecular testing showed that she is a compound heterozygote for mutations in the diastrophic dysplasia sulfate transporter gene (DTDST). This finding confirms that there is locus heterogeneity in apparent Desbuquois dysplasia. It also expands the phenotypic spectrum of disorders caused by mutations in DTDST.

Prenatal diagnosis of isolated femoral bent bone skeletal dysplasia: problems in differential diagnosis and genetic counseling.

Severe localized and symmetric bowing of the femora, in the absence of other significant skeletal or nonskeletal abnormalities, is a rare prenatal ultrasound finding. A 38-year-old woman was referred at 19 weeks gestation and ultrasound of the fetus showed severe shortening, and marked symmetric bowing of the femora. A provisional diagnosis of kyphomelic dysplasia (KD) was made. The patient elected termination of pregnancy and post mortem assessments were most consistent with kyphomelic dysplasia. KD is bent-bone skeletal dysplasia that, in contrast to campomelic dysplasia, involves principally the femora with relative sparing of the remainder of the skeleton. KD can be difficult to distinguish, particularly from symmetric cases of femoral hypoplasia unusual facies syndrome (FH-UFS), and few prenatal diagnoses have been reported. Because KD is thought to an be autosomal recessive disorder, the possibility that definitive diagnosis may not be possible prenatally, and even by postmortem assessment in cases choosing to abort, is an important counseling consideration.

Hajdu--Cheney syndrome: evolution of phenotype and clinical problems.

Hajdu-Cheney syndrome is a rare, autosomal dominant disorder comprising acroosteolysis of the distal phalanges with associated digital abnormalities, distinctive craniofacial and skull changes, dental anomalies, and proportionate short stature. The clinical and radiologic characteristics of Hajdu-Cheney syndrome develop and progress with age. Many of the medical problems that arise in this syndrome cluster in specific age ranges. Case reports of six affected individuals in two additional families and a summary of the English literature is presented with emphasis on the changing physical findings and medical sequelae over time.

Absence of correlation between infantile hypotonia and foramen magnum size in achondroplasia.

Virtually all infants with achondroplasia exhibit variably severe hypotonia in infancy. This hypotonia contributes to delays in motor development and risks for sudden death. Some have proposed that this hypotonia is a direct result of impaired function of long tracts of the spinal cord, secondary to the intrinsic narrowing of the foramen magnum, which also is present in variable severity in all children with achondroplasia. We postulated that if foraminal constriction causes infantile hypotonia, then there should be a strongly positive correlation between foraminal size and severity of hypotonia. Therefore, clinical and computed tomographic data in 71 infants were retrospectively reviewed. We found no correlation. These results suggest that there is no direct relationship and foraminal size does not affect severity of hypotonia. Other potential explanations for this infantile hypotonia are considered.

Autosomal recessive disorder otospondylomegaepiphyseal dysplasia is associated with loss-of-function mutations in the COL11A2 gene.

Otospondylomegaepiphyseal dysplasia (OSMED) is an autosomal recessive skeletal dysplasia accompanied by severe hearing loss. The phenotype overlaps that of the autosomal dominant disorders-Stickler and Marshall syndromes-but can be distinguished by disproportionately short limbs, severe hearing loss, and lack of ocular involvement. In one family with OSMED, a homozygous Gly-->Arg substitution has been described in COL11A2, which codes for the alpha2 chain of type XI collagen. We report seven further families with OSMED. All affected individuals had a remarkably similar phenotype: profound sensorineural hearing loss, skeletal dysplasia with limb shortening and large epiphyses, cleft palate, an extremely flat face, hypoplasia of the mandible, a short nose with anteverted nares, and a flat nasal bridge. We screened affected individuals for mutations in COL11A2 and found different mutations in each family. Individuals from four families, including three with consanguineous parents, were homozygous for mutations. Individuals from three other families, in whom parents were nonconsanguineous, were compound heterozygous. Of the 10 identified mutations, 9 are predicted to cause premature termination of translation, and 1 is predicted to cause an in-frame deletion. We conclude that the OSMED phenotype is highly homogenous and results from homozygosity or compound heterozygosity for COL11A2 mutations, most of which are predicted to cause complete absence of alpha2(XI) chains.

Mild hypophosphatasia mimicking severe osteogenesis imperfecta in utero: bent but not broken.

We describe a fifth instance of hypophosphatasia presenting with prenatal findings suggestive of a very severe bone dysplasia but with a subsequently benign course. Spontaneous improvement of long-bone angulation began prenatally. The postnatal course has been encouraging. This sixth clinical form of hypophosphatasia, which we suggest should be called the benign prenatal form of hypophosphatasia, should be added to the differential diagnostic possibilities considered when angulation or bowing of long bones is discovered prenatally.

Mutations in the CCN gene family member WISP3 cause progressive pseudorheumatoid dysplasia.

Members of the CCN (for CTGF, cyr61/cef10, nov) gene family encode cysteine-rich secreted proteins with roles in cell growth and differentiation. Cell-specific and tissue-specific differences in the expression and function of different CCN family members suggest they have non-redundant roles. Using a positional-candidate approach, we found that mutations in the CCN family member WISP3 are associated with the autosomal recessive skeletal disorder progressive pseudorheumatoid dysplasia (PPD; MIM 208230). PPD is an autosomal recessive disorder that may be initially misdiagnosed as juvenile rheumatoid arthritis. Its population incidence has been estimated at 1 per million in the United Kingdom, but it is likely to be higher in the Middle East and Gulf States. Affected individuals are asymptomatic in early childhood. Signs and symptoms of disease typically develop between three and eight years of age. Clinically and radiographically, patients experience continued cartilage loss and destructive bone changes as they age, in several instances necessitating joint replacement surgery by the third decade of life. Extraskeletal manifestations have not been reported in PPD. Cartilage appears to be the primary affected tissue, and in one patient, a biopsy of the iliac crest revealed abnormal nests of chondrocytes and loss of normal cell columnar organization in growth zones. We have identified nine different WISP3 mutations in unrelated, affected individuals, indicating that the gene is essential for normal post-natal skeletal growth and cartilage homeostasis.

Jugular bulb dehiscence in achondroplasia.

Jugular bulb dehiscence--complete absence of a roof over the jugular bulb--is a rare malformation, probably present in <<< 1% of the general pediatric population. Of 126 children with achondroplasia evaluated in the Midwest Regional Bone Dysplasia Clinic, four and probably five, were identified as having such dehiscence (at least 3.2% of the children assessed). Identifying this increased incidence in achondroplasia is of some clinical relevance, particularly including risk of difficult to control bleeding at myringotomy. It may also present as otherwise unexplained hearing loss, tinnitus and self audible bruits in these children.

Atelosteogenesis type III: long term survival, prenatal diagnosis, and evidence for dominant transmission.

We describe two additional instances of atelosteogenesis, type III, in a woman and her son. Clinical and radiographic information concerning these individuals allows further definition of this rare skeletal dysplasia. This is the first documentation of survival to adulthood of an individual with this disorder, of prenatal diagnostic assessment of an affected individual, and of vertical transmission suggestive of autosomal dominant inheritance. The clinical and radiologic phenotype of atelosteogenesis, type III overlaps with that of another skeletal dysplasia, autosomal dominant Larsen syndrome; these most likely represent allelic conditions.

Obstructive sleep apnea in children with achondroplasia: surgical and anesthetic considerations.

OBJECTIVE: To evaluate the prevalence of obstructive sleep apnea in a large population of children with achondroplasia and to evaluate the effectiveness of adenoidectomy and/or tonsillectomy as treatment. METHODS: Retrospective review of 95 children with achondroplasia. RESULTS: Thirty-six patients (38%) had clinical evidence of obstructive sleep apnea. Thirty-four patients underwent surgery, with more than 1 procedure required in 10 children (29%). Adenotonsillectomy was the initial procedure for 22 of 34 patients, and further therapy was required in only 18% of this group. Adenoidectomy was the initial procedure for 10 of 34, with 90% requiring further surgery for recurrent obstructive sleep apnea. Tonsillectomy alone was performed in 2 patients: 1 was effectively treated and 1 later required adenoidectomy. Endotracheal intubation was accomplished in all patients without complication; 53% required a smaller endotracheal tube than would be predicted by their age. Eight postoperative complications were recorded. CONCLUSIONS: Obstructive sleep apnea is very common in children with achondroplasia. Surgery is effective, but recurrent symptoms are common, particularly when the initial procedure is adenoidectomy. The complication rate is higher than that observed in a general pediatric population but is readily managed with standard therapy. Anesthesia can be given safely to these patients with special consideration for limited neck extension and appropriate endotracheal tube size.

Autosomal dominant hypohidrotic ectodermal dysplasia in a large family.

We have studied an autosomal dominant hypohidrotic ectodermal dysplasia in 38 individuals over six generations in one family. Thirty-two affected individuals in four generations are still living. Questionnaire responses were received from 21 of the affected relatives and some of the individuals were examined by one of the authors. Smooth, dry, thin skin is seen in most affected individuals. Nearly all have fine, slow-growing scalp and body hair and all have sparse eyebrows and short eyelashes. Nearly all show a decrease in sweating, with some only sweating under the arms and/or on the palms and soles. All affected individuals lacked some deciduous teeth and some permanent teeth. Some teeth are abnormally shaped. Nail abnormalities are more variable and may occur more frequently with increasing age. No other abnormalities are seen in affected individuals in this family. We reviewed 40 autosomal dominant ectodermal dysplasia syndromes. This family bears some resemblance to a family described by Jorgensen et al. [1987]; however, it appears to represent a disorder that has not been described previously.

Long-term survival in typical thanatophoric dysplasia type 1.

Thanatophoric dysplasia (TD), a severe skeletal dysplasia, is virtually always lethal neonatally, although a few previous reports have documented survival up to 4.75 years. We present a patient with survival beyond age 9 years and summarize his growth, development and medical history. The common Arg248Cys mutation in the extracellular region of fibroblast growth factor receptor 3 (FGFR3) was identified, eliminating the possibility that his long-term survival is attributable to an atypical mutation. This patient (and at least one other TD long-term survivor) have a rare skin disorder, acanthosis nigricans, which also occurs in Crouzon syndrome when caused by a FGFR3 mutation. Therefore, any molecular model of the origin of acanthosis nigricans secondary to FGFR3 mutations must account for the association of diverse mutations and these cutaneous effects.

Biophysical bases for delayed and aberrant motor development in young children with achondroplasia.

Achondroplasia, the most common skeletal dysplasia, is characterized by delayed and aberrant motoric development in childhood. Delays and aberrancy are secondary to the anatomical differences inherent in people with achondroplasia. We present a photographic essay documenting biophysical differences, aberrant pre-orthograde movement strategies, and selected adaptive techniques. A parental questionnaire assessed the presence of, predominance, and ages at which various types of pre-orthograde locomotion were observed. Fine and gross motor skills were assessed contemporaneously by use of the Denver Developmental Screening Test in 93 children with achondroplasia and were found to be more delayed than previously reported. Physicians, therapists, early-childhood educators, and parents should recognize that aberrant does not mean maladaptive and that different development is not defective development.

Somatic mosaicism in Fanconi anemia: molecular basis and clinical significance.

Approximately 25% of patients with Fanconi anemia (FA) have evidence of spontaneously occurring mosaicism as manifest by the presence of two subpopulations of lymphocytes, one of which is hypersensitive to cross-linking agents (e.g. mitomycin C) while the other behaves normally in response to these agents. The molecular basis of this phenotypic reversion has not yet been determined. We have investigated 8 FA patients with evidence of mosaicism. Epstein-Barr virus-immortalized lymphoblastoid cell lines established from these patients exhibited an IC50 for mitomycin C of 25 to > 100 nM compared to a mean of 2 +/- 2 nM for 20 nonmosaic FA patients and 49 +/- 11 nM for 8 healthy controls. In 3 patients who were compound heterozygotes for pathogenic FAC gene mutations the molecular mechanism of the mosaicism was investigated by haplotype analysis. The results indicated that an intragenic mitotic recombination must have occurred leading to a segregation of a wild-type allele in the reverted cells and suggested two patterns of recombination. In 1 patient a single intragenic crossover between the maternally and paternally inherited mutations occurred associated with markers located distally to the FAC gene; in the other 2 patients (sibs) the mechanism appears to have been gene conversion resulting in segregants which have lost one pathogenic mutation. In 6 of the 8 patients the hematological symptoms were relatively mild despite an age range of 9-30 years.

Fine mapping of the nail-patella syndrome locus at 9q34.

Nail-patella syndrome (NPS), or onychoosteodysplasia, is an autosomal dominant, pleiotropic disorder characterized by nail dysplasia, absent or hypoplastic patellae, iliac horns, and nephropathy. Previous studies have demonstrated linkage of the nail-patella locus to the ABO and adenylate kinase loci on human chromosome 9q34. As a first step toward isolating the NPS gene, we present linkage analysis with 13 polymorphic markers in five families with a total of 69 affected persons. Two-point linkage analysis with the program MLINK showed tight linkage of NPS and the anonymous markers D9S112 (LOD = 27.0; theta = .00) and D9S315 (LOD = 22.0; theta = .00). Informative recombination events place the NPS locus within a 1-2-cM interval between D9S60 and the adenylate kinase gene (AK1).

Prevention of fixed, angular kyphosis in achondroplasia.

Transient kyphotic deformity arises in most infants with achondroplasia. In a minority, a fixed and angular kyphosis develops, which can cause serious neurologic sequelae later in life. We assessed a protocol for preventing development of such fixed kyphosis in a sequential, unselected series of 66 infants with achondroplasia. This study demonstrates the efficacy of early prohibition of unsupported sitting and, in those in whom such prohibition proves insufficient, use of bracing. When the proposed algorithm was followed, none of the infants had development of a progressive kyphotic deformity. On this basis, it appears that the secondary risks of angular kyphosis, previously estimated to be between 10 and 15% in individuals with achondroplasia, can be completely eliminated.

Errors in the prenatal diagnosis of children with achondroplasia.

To provide data about the frequency of prenatal misdiagnosis in achondroplasia (Ach), we retrospectively abstracted data from 37 consecutive referrals of infants with Ach where ultrasound was performed prenatally. Nine of 37 (24 per cent) had a positive family history of Ach; all nine were correctly diagnosed prenatally. Of the 28 with no family history of Ach, 16 (57 per cent) were recognized to have abnormalities on ultrasound but none was given a definite diagnosis of Ach. Five families received an appropriate diagnosis of "most likely' Ach and four others were given a non-specific (but appropriate) diagnosis of some dwarfing disorder, not otherwise specified. In seven instances (25 per cent), an incorrect diagnosis of a lethal or very severe disorder was provided. These results illustrate the difficulty of making a specific prenatal diagnosis of Ach. In the face of the resulting uncertainty, physicians appear to elect to emphasize the most severe of alternative diagnoses. Given the homogeneity of mutations within the fibroblast growth factor receptor 3 (FGFR3) gene in the vast majority of patients with Ach, FGFR3 mutational analysis can be offered in every instance where a short-limb disorder is ultrasonographically detected in the latter stages of pregnancy. This would reduce the amount of incorrect and potentially harmful information provided to families.

Standard curves of chest circumference in achondroplasia and the relationship of chest circumference to respiratory problems.

Several pathogenetic factors, alone or in combination, may contribute to the increased frequency of respiratory complications in achondroplasia. It has been suggested that relatively small chest circumference sometimes may contribute. However, there are no published curves of chest circumference for age in achondroplasia with which to compare patients. Nor are there data relating chest circumference to overall size in achondroplasia. We present curves of chest circumference for males and females with achondroplasia from birth through age 7 years. Additional curves for chest circumference against height are also provided. Finally, we report some preliminary data regarding the possible association of chest size with respiratory signs and symptoms.

Patterson-Lowry rhizomelic dysplasia: a possible second example.

We present a possible example of Patterson-Lowry rhizomelic dysplasia. If so, this is only the second reported individual with this disorder and the first instance of its recognition in a child. Clinical features in this child are compared with the other described individual and differential diagnosis is discussed. Primary features include rhizomelic foreshortening most markedly affecting the arms, limitation of shoulder abduction, mild generalized foreshortening of the long bones, mild short stature, coxa vara, and specific radiological features.