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.

Microdissection-based high-resolution genomic array analysis of two patients with cytogenetically identical interstitial deletions of chromosome 1q but distinct clinical phenotypes.

We describe two boys with cytogenetically identical interstitial deletions in the q42.11-q42.13 region of the long arm of chromosome 1 detected by high-resolution G-banding analysis. These children share some phenotypic features but also exhibit distinct morphologic differences. We further characterized the deletions using a new technical strategy--microdissection-based high-resolution genomic array (MHGA) analysis--to define the breakpoints, genomic sizes, and gene contents of the deletions. This showed that the patients had distinguishable deletions that were adjacent but did not overlap, thus explaining the observed phenotypic differences. These results were surprising because we expected at least some degree of overlap to explain the features that were shared. MHGA can quickly give precise and detailed information about any rearrangement in the genome using as little material as a single cell. This novel strategy provides unique advantages for both clinical diagnosis and genomic research.

An analysis of PAX1 in the development of vertebral malformations.

An analysis of PAX1 in the development of vertebral malformations. Due to the sporadic occurrence of congenital vertebral malformations, traditional linkage approaches to identify genes associated with human vertebral development are not possible. We therefore identified PAX1 as a candidate gene in vertebral malformations and congenital scoliosis due to its mutation in the undulated mouse. We performed DNA sequence analysis of the PAX1 gene in a series of 48 patients with congenital vertebral malformations, collectively spanning the entire vertebral column length. DNA sequence coding variants were identified in the heterozygous state in exon 4 in two male patients with thoracic vertebral malformations. One patient had T9 hypoplasia, T12 hemivertebrae and absent T10 pedicle, incomplete fusion of T7 posterior elements, ventricular septal defect, and polydactyly. This patient had a CCC (Pro)-->CTC (Leu) change at amino acid 410. This variant was not observed in 180 chromosomes tested in the National Institute of Environmental Health Sciences (NIEHS) single nucleotide polymorphism (SNP) database and occurred at a frequency of 0.3% in a diversity panel of 1066 human samples. The second patient had a T11 wedge vertebra and a missense mutation at amino acid 413 corresponding to CCA (Pro)-->CTA (Leu). This particular variant has been reported to occur in one of 164 chromosomes in the NIEHS SNP database and was found to occur with a similar frequency of 0.8% in a diversity panel of 1066 human samples. Although each patient's mother was clinically asymptomatic and heterozygous for the respective variant allele, the possibility that these sequence variants have clinical significance is not excluded.

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.

Klippel-Feil anomaly with Sprengel anomaly, omovertebral bone, thumb abnormalities, and flexion-crease changes: novel association or syndrome?

We report on a family with Klippel-Feil anomaly (KF), Sprengel anomaly, omovertebral bone, thumb abnormalities, and flexion-crease abnormalities. This combination of abnormalities does not fit into Holt-Oram syndrome, Wildervanck syndrome, oculo-auriculo-vertebral (Goldenhar) anomaly, or the VATER complex. Clinical aspects of a KF classification are discussed. The state of molecular research on KF is briefly reported. We conclude that this set of anomalies is a novel combination, probably representing pleiotropy of a single Mendelian gene.

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.

Detection of chromosomal aberrations by a whole-genome microsatellite screen.

Chromosomal aberrations are a common cause of multiple anomaly syndromes that include developmental and growth retardation. Current microscopic techniques are useful for the detection of such aberrations but have a limit of resolution that is above the threshold for phenotypic effect. We hypothesized that a genomewide microsatellite screen could detect chromosomal aberrations that were not detected by standard cytogenetic techniques in a portion of these individuals. To test this hypothesis, we performed a genomewide microsatellite screen of patients, by use of a currently available genetic-marker panel that was originally designed for meiotic mapping of Mendelian traits. We genotyped approximately 400 markers on 17 pairs of parents and their children who had normal karyotypes. By using this approach, we detected and confirmed two cases of segmental aneusomy among 11 children with multiple congenital anomalies. These data demonstrate that a genomewide microsatellite scan can be used to detect chromosomal aberrations that are not detected by microscopic techniques.

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.

Filippi syndrome: report of three additional cases.

Filippi syndrome is an autosomal recessive condition characterized by variable soft tissue syndactyly of the fingers and toes, microcephaly, pre- and postnatal growth retardation, mildly abnormal craniofacial appearance, and mental retardation. We report on three unrelated individuals with Filippi syndrome. All have microcephaly, minor facial anomalies, variable syndactyly of digits, growth impairment, and developmental delay. One patient also has polydactyly, which has not been reported previously in the Filippi syndrome.

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.

Genetic localization of a new locus for recessive familial spastic paraparesis to 15q13-15.

OBJECTIVE: To characterize a new gene locus for familial spastic paraparesis (FSP). BACKGROUND: FSP is a genetically heterogeneous group of upper motor neuron syndromes. It can be inherited as an autosomal dominant, autosomal recessive, or X-linked disorder. Four loci for autosomal dominant FSP have been genetically mapped, and two genes have been shown responsible for the X-linked type. In addition, two loci for autosomal recessive type have been reported and mapped to chromosomes 8q and 16q. The gene for the 16q locus has been characterized as a mitochondrial protein. METHODS: Eight recessive FSP families from America and Europe were used for genetic linkage analysis. The known recessive loci (8q and 16q) and the X-linked loci (PLP and L1CAM genes) were screened through PCR amplification, followed by linkage analysis, single-strand conformational polymorphism, or both. RESULTS: All the families except one revealed lack of linkage to the known loci for recessive and X-linked types of FSP. One of the eight families showed data consistent with linkage to the previously characterized 8q locus. Analysis of all the families for possible linkage to other candidate loci revealed significant positive lod scores for markers in chromosome 15q. The maximum multipoint combined lod score for the non-8q families was Z = 3.14 for markers D15S1007, D15S971, D15S118, and D15S1012, at a distance of 6.41 cM from the marker D15S1007, in between D15S971 and D15S118. CONCLUSIONS: Our data suggest a new locus for recessive FSP linked to chromosome 15q, and that this may be the most common one.

Ventricular noncompaction and distal chromosome 5q deletion.

We describe a 7 1/2-year-old girl with mildly unusual phenotype and complex heart disease including ventricular myocardial noncompaction. She was found to have a distal 5q deletion, del(5)(q35.1q35.3). Fluorescent in situ hybridization showed that this deletion included the locus for the cardiac specific homeobox gene, CSX. This suggests that some instances of ventricular myocardial noncompaction may be caused by haploinsufficiency of CSX.

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.

Molecular analysis of SALL1 mutations in Townes-Brocks syndrome.

Townes-Brocks syndrome (TBS) is an autosomal dominantly inherited malformation syndrome characterized by anal, renal, limb, and ear anomalies. Recently, we showed that mutations in the putative zinc finger transcription factor gene SALL1 cause TBS. To determine the spectrum of SALL1 mutations and to investigate the genotype-phenotype correlations in TBS, we examined 23 additional families with TBS or similar phenotypes for SALL1 mutations. In 9 of these families mutations were identified. None of the mutations has previously been described. Two of these mutations are nonsense mutations, one of which occurred in three unrelated families. Five of the mutations are short deletions. All of the mutations are located 5' of the first double zinc finger (DZF) encoding region and are therefore predicted to result in putative prematurely terminated proteins lacking all DZF domains. This suggests that only SALL1 mutations that remove the DZF domains result in TBS. We also present evidence that in rare cases SALL1 mutations can lead to phenotypes similar to Goldenhar syndrome. However, phenotypic differences in TBS do not seem to depend on the site of mutation.

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.