The heterogeneity of craniofacial morphology in Prader-Willi patients.

Prader-Willi syndrome is a complex genetic disorder with narrow spectrum of facial phenotypic signs, which make the clinical diagnosis difficult in some cases. There are several reports describing the craniofacial appearance of Prader-Willi patients, but there are only a few cephalometric studies for these patients. In this study were included 18 patients with Prader-Willi syndrome and a control group of 18 subjects of both sexes selected based on specific criteria. The cephalometric radiographs of the patients were taken using the standardized technique with centric teeth in occlusion and lips in relaxed position. Angular, horizontal and linear measurements were analyzed for the study group and for the control group. We established that in Prader-Willi patients, there is a decrease of the majority of parameters but the degree of this reduction varies widely between patients and clinically typical facies not always have smaller measurements which can be found in an unusual facies. Facial dysmorphism in Prader-Willi patients varies a group ranging from miss proportions that do not alter the facial architecture as regard of facial typology, skeletal class and pattern of development to a severe disturbance of those. There is a degree of clinical heterogeneity between subjects with Prader-Willi syndrome on clinical evaluation and cephalometric study confirms the heterogeneity for this patients. Because the identification of smaller dimensions for majority of parameters in children and adults, the possibility of developmental delay or growth retardation delay can be excluded. These findings are important for the orthodontist for optimum timing of orthodontic management of patients with Prader-Willi syndrome.

X-linked congenital adrenal hypoplasia with hypogonadotropic hypogonadism caused by an inversion disrupting a conserved noncoding element upstream of the NR0B1 (DAX1) gene.

CONTEXT: X-linked congenital adrenal hypoplasia with hypogonadotropic hypogonadism (AHCH) is known to be caused by coding mutations in the nuclear receptor subfamily 0, group B, member 1 (NR0B1) gene, encoding the transcriptional repressor dosage-sensitive sex-reversal adrenal hypoplasia critical region on the X chromosome protein 1 (DAX1). OBJECTIVE/PATIENTS: Four males in a family were affected by AHCH. Our aim was to locate the genetic cause of their disease, knowing that they had no mutation in the obvious candidate gene, NR0B1. DESIGN: Linkage analysis of the X chromosome and mutational screening of conserved noncoding regions upstream of NR0B1 were performed. To functionally characterize the genetic defect, studies of transcription and expression of DAX1 and steroidogenic factor 1 (SF-1) were done. RESULTS: A 60 Mb inversion on the X chromosome with one of the inversion breakpoints located in a conserved noncoding region 4 kb upstream of NR0B1 was detected. The inversion causes relocation of a putative SF-1 binding site implicated in murine gonadal development. A reporter construct lacking this enhancer element upstream of NR0B1 was unresponsive to SF-1 transcriptional activation. Immunohistochemistry suggested that the inversion leads to SF-1 silencing in the patients' testes both in childhood and in adult life. CONCLUSION: We report a noncoding mutation causing AHCH, an inversion resulting in a phenotype similar to what is caused by intragenic NR0B1 null mutations. The inversion seems to disrupt and/or relocate regulatory sites crucial in DAX1 expression.

15q overgrowth syndrome: a newly recognized phenotype associated with overgrowth, learning difficulties, characteristic facial appearance, renal anomalies and increased dosage of distal chromosome 15q.

Trisomy and tetrasomy of distal chromosome 15q have rarely been reported. Although most of the described patients have some learning difficulties and are overgrown, the phenotype associated with distal trisomy/tetrasomy 15q is uncertain due to the small numbers of reported cases and the common co-occurrence of additional chromosome deletions in many patients with trisomy 15q. We present five individuals with overgrowth, learning difficulties and increased dosage of distal 15q. Partial trisomy 15q was identified in four of these cases. Two were generated through recombination of a parental pericentric inversion and two were generated through malsegregation of a maternal balanced 14;15 reciprocal translocation. In all four cases the trisomy can be considered "pure" as the 14p and 15p monosomies will exert no phenotypic effect. Partial tetrasomy 15q, as the result of an analphoid supernumerary chromosome derived from an inverted duplication of distal 15q, was identified in the fifth patient. In addition to the overgrowth and learning difficulties, all five had a characteristic facial appearance and three had renal anomalies. The gestalt consists of a long, thin face with a prominent chin and nose. Renal anomalies included renal agenesis, horseshoe kidney, and hydronephrosis. We provide further support for a distinct "15q overgrowth syndrome" caused by either trisomy or tetrasomy resulting in increased dosage of distal 15q. In addition we propose that renal anomalies and a distinctive facial appearance be considered major features of this condition.

Severe hypohidrotic ectodermal dysplasia in a girl caused by a de novo 9;X insertion that includes XIST and disrupts the EDA gene.

X-linked hypohidrotic ectodermal dysplasia (XLHED) is caused by mutations in the EDA gene. A girl with severe hypohidrotic ectodermal dysplasia and normal mental development had completely skewed X chromosome inactivation with only the paternal X active in peripheral blood cells. Routine chromosome analysis and sequencing of the EDA gene were normal. However, whole chromosome painting revealed a 9;X insertion. FISH analyses with BAC probes towards the EDA gene and the more distal region containing the XIST locus showed that an X chromosome fragment of at least 4 Mb containing XIST was inserted into 9p13 in conjunction with a de novo pericentric inversion of chromosome 9. The proximal breakpoint was within the EDA gene and the distal breakpoint was distal to the XIST locus. Both parents had normal chromosomes, and the mother had random X inactivation in peripheral blood cells. Because XIST was lacking on the X chromosome with the disrupted EDA gene, the normal X chromosome was inactivated resulting in severe XLHED.