A family with autosomal dominant oculo-auriculo-vertebral spectrum.

Oculo-auriculo-vertebral spectrum (MIM 164210) is a term suggested by Gorlin to summarize the different phenotypic expressions of a continuum that has been known as hemifacial microsomia, Goldenhar syndrome, or first and second branchial arch anomalies. The different terms indicate the extremely variable clinical findings, including especially defects of aural, oral and mandibular development. Additionally, cardiac, renal, skeletal and other anomalies occur. The majority of oculo-auriculo-vertebral spectrum cases are sporadic; nevertheless, several families have been reported with proof of both autosomal dominant and autosomal recessive inheritance. We describe a family with transmission of oculo-auriculo-vertebral spectrum from a mother to her two daughters indicating an autosomal dominant mode of inheritance. Our literature review reveals that patients with autosomal dominant inheritance of oculo-auriculo-vertebral spectrum are more often bilaterally affected than patients with sporadic occurrence of oculo-auriculo-vertebral spectrum. In addition, hearing loss, absent or narrow external auditory canal, anomalies of the mouth and epibulbar dermoids seem to occur less frequently in patients with autosomal dominant oculo-auriculo-vertebral spectrum compared with sporadic oculo-auriculo-vertebral spectrum.

Oculo-auriculo-vertebral spectrum (OAVS): clinical evaluation and severity scoring of 53 patients and proposal for a new classification.

Oculo-auriculo-vertebral spectrum (OMIM164210) is a phenotypically and probably also a genetically heterogeneous disorder, characterized by anomalies of the ear (mostly microtia), hemifacial microsomia, and defects of the vertebral column. Associated clinical findings include anomalies of the eye and brain, and developmental delay. We have evaluated the clinical data and photographs of 53 unrelated patients with OAVS, all presenting with either isolated microtia or preauricular tags in association with hemifacial microsomia as minimal diagnostic criteria; five had a positive family history for OAVS. Based on the main clinical findings and unilateral or bilateral involvement, we have developed a new classification system for OAVS, consisting of six subgroups. There is a statistically significant correlation between the subgroup and number of associated clinical findings, and a statistically significant difference regarding prognosis in uni- and bilaterally affected patients, suggesting that this classification is clinically relevant to the categorization of patients with OAVS. The newly developed scoring system (two points for each main clinical finding and one for each associated clinical finding) presented here, also aids prognosis, especially for delay of motor development and brain anomalies, and statistical analysis revealed significant clustering between different clinical findings of OAVS confirming the clinical impression previously published by several authors.

Spectrum of mutations in PTPN11 and genotype-phenotype correlation in 96 patients with Noonan syndrome and five patients with cardio-facio-cutaneous syndrome.

Noonan syndrome (NS) is a relatively common, but genetically heterogeneous autosomal dominant malformation syndrome. Characteristic features are proportionate short stature, dysmorphic face, and congenital heart defects. Only recently, a gene involved in NS could be identified. It encodes the non-receptor protein tyrosine phosphatase SHP-2, which is an important molecule in several intracellular signal transduction pathways that control diverse developmental processes, most importantly cardiac semilunar valvulogenesis. We have screened this gene for mutations in 96 familial and sporadic, well-characterised NS patients and identified 15 different missense mutations in a total of 32 patients (33%), including 23 index patients. Most changes clustered in one exon which encodes parts of the N-SH2 domain. Five of the mutations were recurrent. Interestingly, no mutations in the PTPN11 gene were detected in five additional patients with cardio-facio-cutaneous (CFC) syndrome, which shows clinical similarities to NS.

Mutations in NSD1 are responsible for Sotos syndrome, but are not a frequent finding in other overgrowth phenotypes.

Recently, deletions encompassing the nuclear receptor binding SET-Domain 1 (NSD1) gene have been described as the major cause of Japanese patients with the Sotos syndrome, whereas point mutations have been identified in the majority of European Sotos syndrome patients. In order to investigate a possible phenotype-genotype correlation and to further define the predictive value of NSD1 mutations, we performed mutational analysis of the NSD1 gene in 20 patients and one familial case with Sotos syndrome, five patients with Weaver syndrome, six patients with unclassified overgrowth/mental retardation, and six patients with macrocephaly/mental retardation. We were able to identify mutations within the NSD1 gene in 18 patients and the familial case with Sotos syndrome (90%). The mutations (six nonsense, eight frame shifts, three splice site, one missense, one in-frame deletion) are expected to result in an impairment of NSD1 function. The best correlation between clinical assessment and molecular results was obtained for the Sotos facial gestalt in conjunction with overgrowth, macrocephaly, and developmental delay. In contrast to the high mutation detection rate in Sotos syndrome, none of the patients with Weaver syndrome, unclassified overgrowth/mental retardation and macrocephaly/mental retardation, harbored NSD1 mutations. We tested for large deletions by FISH analysis but were not able to identify any deletion cases. The results indicate that the great majority of patients with Sotos syndrome are caused by mutations in NSD1. Deletions covering the NSD1 locus were not found in the patients analyzed here.

Molecular cytogenetic characterization of a 10p14 deletion that includes the DGS2 region in a patient with multiple anomalies.

We report on a prenatally diagnosed four-month-old boy with DiGeorge-like phenotype and a deletion of chromosome 10pter --> 14. Fluorescence in situ hybridization (FISH) experiments using phage artificial chromosome (PAC) and yeast artificial chromosome (YAC) clones indicated that the chromosomal breakpoint was located at the proximal boundary of the DiGeorge syndrome 2 (DGS2) critical region. The patient demonstrated a high forehead, high arched eyebrows, short palpebral fissures, sparse eyelashes, prominent nose with bulbous tip, small mouth, receding chin, round ears with deficient helices, cardiac defects atrial septal defect (ASD), ventricular septal defect (VSD), mild brachytelephalangy, mild syndactyly, hypoplastic left kidney, undescended testes, muscular hypertonia, dorsally flexed big toes, and developmental delay. The phenotype corresponded well with the clinical signs of 10p deletion of this region that were described previously. The facial features appeared different from the typical face with the 22q11 deletion.

Unbalanced cryptic translocation der(14)t(9;14)(q34.3;q32.33) identified by subtelomeric FISH.

We investigated a girl with dysmorphic features and moderate developmental delay by subtelomeric FISH (fluorescence in-situ hybridization). We found an unbalanced cryptic translocation, t(9;14)(q34.3;q32.33), resulting in a subtelomeric deletion of 14q and duplication of 9q deriving from a balanced translocation in the mother. A review of the literature suggests that the phenotype of our case is related to the 14 qter deletion, without signs of concomitant partial trisomy 9. The case reinforces the value of subtelomeric screening for genetic counselling.

Clinical, cytogenetic, and molecular observations in a patient with Pallister-Killian-syndrome with an unusual karyotype.

Pallister-Killian syndrome is a clinically recognizable syndrome, usually due to a tissue-limited mosaicism for a supernumary 12p isochromosome (i12p). Here we report an unusual case with tetrasomy/trisomy/disomy 12p mosaic in fibroblasts and trisomy/disomy 12p mosaic in lymphocytes. The tetrasomy 12p was due to an i12p, the trisomy 12p to a single 12p marker. Both marker chromosomes were investigated with conventional cytogenetic techniques and fluorescent in situ hybridization (FISH). Stability under culturing conditions was studied. DNA-analysis revealed prezygotic maternal origin of the extra 12p material. Clinically, the patient seems to have less retardation than most patients with Pallister-Killian syndrome.

A 117-kb microdeletion removing HOXD9-HOXD13 and EVX2 causes synpolydactyly.

Studies in mouse and chick have shown that the 5' HoxD genes play major roles in the development of the limbs and genitalia. In humans, mutations in HOXD13 cause the dominantly inherited limb malformation synpolydactyly (SPD). Haploinsufficiency for the 5' HOXD genes has recently been proposed to underlie the monodactyly and penoscrotal hypoplasia in two children with chromosomal deletions encompassing the entire HOXD cluster. Similar deletions, however, have previously been associated with split-hand/foot malformation (SHFM), including monodactyly. Here we report a father and daughter with SPD who carry a 117-kb microdeletion at the 5' end of the HOXD cluster. By sequencing directly across the deletion breakpoint, we show that this microdeletion removes only HOXD9-HOXD13 and EVX2. We also report a girl with bilateral split foot and a chromosomal deletion that includes the entire HOXD cluster and extends approximately 5 Mb centromeric to it. Our findings indicate that haploinsufficiency for the 5' HOXD genes causes not SHFM but SPD and point to the presence of a novel locus for SHFM in the interval between EVX2 and D2S294. They also suggest that there is a regulatory region, upstream of the HOXD cluster, that is responsible for activating the cluster as a whole.

Mutations in bone morphogenetic protein receptor 1B cause brachydactyly type A2.

Brachydactyly (BD) type A2 is an autosomal dominant hand malformation characterized by shortening and lateral deviation of the index fingers and, to a variable degree, shortening and deviation of the first and second toes. We performed linkage analysis in two unrelated German families and mapped a locus for BD type A2 to 4q21-q25. This interval includes the gene bone morphogenetic protein receptor 1B (BMPR1B), a type I transmembrane serinethreonine kinase. In one family, we identified a T599 --> A mutation changing an isoleucine into a lysine residue (I200K) within the glycine/serine (GS) domain of BMPR1B, a region involved in phosphorylation of the receptor. In the other family we identified a C1456 --> T mutation leading to an arginine-to-tryptophan amino acid change (R486W) in a highly conserved region C-terminal of the BMPR1B kinase domain. An in vitro kinase assay showed that the I200K mutation is kinase-deficient, whereas the R486W mutation has normal kinase activity, indicating a different pathogenic mechanism. Functional analyses with a micromass culture system revealed a strong inhibition of chondrogenesis by both mutant receptors. Overexpression of mutant chBmpR1b in vivo in chick embryos by using a retroviral system resulted either in a BD phenotype with shortening and/or missing phalanges similar to the human phenotype or in severe hypoplasia of the entire limb. These findings imply that both mutations identified in human BMPR1B affect cartilage formation in a dominant-negative manner.