Localized mutations in the gene encoding the cytoskeletal protein filamin A cause diverse malformations in humans.

Remodeling of the cytoskeleton is central to the modulation of cell shape and migration. Filamin A, encoded by the gene FLNA, is a widely expressed protein that regulates re-organization of the actin cytoskeleton by interacting with integrins, transmembrane receptor complexes and second messengers. We identified localized mutations in FLNA that conserve the reading frame and lead to a broad range of congenital malformations, affecting craniofacial structures, skeleton, brain, viscera and urogenital tract, in four X-linked human disorders: otopalatodigital syndrome types 1 (OPD1; OMIM 311300) and 2 (OPD2; OMIM 304120), frontometaphyseal dysplasia (FMD; OMIM 305620) and Melnick-Needles syndrome (MNS; OMIM 309350). Several mutations are recurrent, and all are clustered into four regions of the gene: the actin-binding domain and rod domain repeats 3, 10 and 14/15. Our findings contrast with previous observations that loss of function of FLNA is embryonic lethal in males but manifests in females as a localized neuronal migration disorder, called periventricular nodular heterotopia (PVNH; refs. 3-6). The patterns of mutation, X-chromosome inactivation and phenotypic manifestations in the newly described mutations indicate that they have gain-of-function effects, implicating filamin A in signaling pathways that mediate organogenesis in multiple systems during embryonic development.

Reduced penetrance alleles for Huntington's disease: a multi-centre direct observational study.

OBJECTIVE: To obtain penetrance data for Huntington's disease when DNA results are in the range of 36-39 CAG repeats and assess the consistency of reporting the upper allele from two reference centres. METHOD: Data were collected anonymously on age of onset or age last known to be unaffected from a cohort of individuals with results in this range. DNA samples were re-analysed in two reference centres. Kaplan-Meier analysis was used to construct an age of onset curve and penetrance figures. RESULTS: Clinical data and concordant DNA results from both reference centres were available for 176 samples; penetrance figures (and 95% confidence intervals) for this cohort, at age 65 and 75 years, were 63.9% (55.5% to 73.2%) and 74.2% (64.2% to 84.2%), respectively. Inclusion of 28 additional subjects for whom repeat DNA results were unavailable, obtained from only one reference centre, or discrepant by one repeat within this range, gave penetrance data (including 95% confidence intervals) at ages 65 and 75 years of 62.4% (54.4% to 70.4%) and 72.7.% (63.3% to 82.1%), respectively. 238 duplicate results were available from the reference centres; 10 (4.2%) differed by one CAG repeat in the reporting of the upper allele and in two (0.84%) of these cases the discrepancy was between 39 and 40 repeats. CONCLUSION: When DNA results are in this range, a conservative approach is to say that there is at least a 40% chance the person will be asymptomatic at age 65 years and at least a 30% chance the person will be asymptomatic at age 75 years.

The impact of Juvenile Huntington's Disease on the family: the case of a rare childhood condition.

There has been little research into the impact of Juvenile Huntington's Disease (JHD) on the family, and the issues facing this group are poorly understood. The study reported here is part of larger project that aimed to address this. Ten semi-structured interviews with the main carer were carried out, and were analysed using Interpretative Phenomenological Analysis (IPA). This article reports three themes arising from the study relating to the psychosocial impact of JHD on the family: (1) dealing with something so different; (2) lack of understanding (3) isolation. This information is useful in developing appropriate services for families affected by JHD, as well as being of relevance to other childhood conditions.

Prader-Willi and Klinefelter syndrome: a coincidence or not?

Prader-Willi syndrome is a complex multisystem disorder characterized by neonatal hypotonia, developmental delay, short stature, obesity, behaviour problems, hypothalamic hypogonadism and characteristic appearance. A number of sex chromosome abnormalities have been reported in children with Prader-Willi syndrome. We report on an infant with a 47, XXY karyotype and Prader-Willi syndrome diagnosed at 2 months of age. He is possibly the youngest to be reported with both Prader-Willi syndrome and Klinefelter syndrome. We have shown that the extra X chromosome causing Klinefelter syndrome is paternal in origin and Prader-Willi syndrome is due to maternal heterodisomy indicating that these two events occurred coincidentally.

Caring for a child with Juvenile Huntington's Disease: helpful and unhelpful support.

There has been little research into the psychosocial impact of Juvenile Huntington's Disease on the child and family. This study investigates the social and health care needs of those affected by Juvenile Huntington's Disease. Ten semi-structured interviews with carers were analysed using the qualitative methodology interpretative phenomenological analysis. This article reports three themes on the social support that families received. The first theme describes how parents perceived the support that they received from family and friends. The second and third themes describe how parents perceived helpful and unhelpful experiences of professional support. This corresponds to the view that social support is a 'double-edged sword', which can both ameliorate the effects of, and be a source of, stress. This information should be useful to those supporting the family of a child with a chronic or terminal illness.

Expanding the phenotype of craniofrontonasal syndrome: two unrelated boys with EFNB1 mutations and congenital diaphragmatic hernia.

Craniofrontonasal syndrome (CFNS, MIM 304110) is an X-linked craniofacial disorder that shows paradoxically greater severity in heterozygous females than in hemizygous males. Mutations have been identified in the EFNB1 gene that encodes a member of the ephrin-B family of transmembrane ligands for Eph receptor tyrosine kinases. Here, we describe two unrelated families, in both of which a mother and her son have proven mutations in EFNB1. The mothers have classical features of CFNS; although the sons have no major craniofacial features other than telecanthus, both had a congenital diaphragmatic hernia (CDH). Our cases represent the first in which CDH has been confirmed in males with mutations in EFNB1, highlighting an important role for signalling by ephrin-B1 in the development of the diaphragm.

Genetic professionals' reports of nondisclosure of genetic risk information within families.

Patients attending genetic clinics are often the main gatekeepers of information for other family members. There has been much debate about the circumstances under which professionals may have an obligation, or may be permitted, to pass on personal genetic information about their clients but without their consent to other family members. We report findings from the first prospective study investigating the frequency with which genetics professionals become concerned about the failure of clients to pass on such information to their relatives. In all, 12 UK and two Australian regional genetic services reported such cases over 12 months, including details of actions taken by professionals in response to the clients' failure to disclose information. A total of 65 cases of non-disclosure were reported, representing <1% of the genetic clinic consultations in the collaborating centres during the study period. These included 39 cases of the failure of parents not passing full information to their adult offspring, 22 cases where siblings or other relatives were not given information and four cases where information was withheld from partners -- including former and prospective partners. Professionals reported clients' reasons for withholding information as complex, more often citing concern and the desire to shield relatives from distress rather than poor family relationships. In most cases, the professionals took further steps to persuade their clients to make a disclosure but in no instance did the professional force a disclosure without the client's consent.

Microcephaly-lymphoedema-chorioretinal dysplasia: three cases to delineate the facial phenotype and review of the literature.

Microcephaly-lymphoedema-chorioretinal dysplasia (MIM 152950) has been described as a distinct clinical entity. The mode of inheritance is uncertain, but male to male transmission has been observed supporting autosomal dominant inheritance. A characteristic facial phenotype has recently been suggested. We report three isolated male patients with this condition who have all of the major features and share a distinct facial appearance with upslanting palpebral fissures, a broad nose with rounded tip, anteverted nares, long philtrum with thin upper lip, pointed chin and prominent ears. The clinical features in our patients support the hypothesis of a characteristic facial phenotype in this syndrome.

Managing juvenile Huntington's disease.

Huntington's disease (HD) is a well-recognized progressive neurodegenerative disorder that follows an autosomal dominant pattern of inheritance. Onset is insidious and can occur at almost any age, but most commonly the diagnosis is made between the ages of 35 and 55 years. Onset ≤20 years of age is classified as juvenile HD (JHD). This age-based definition is arbitrary but remains convenient. There is overlap between the clinical pathological and genetic features seen in JHD and more traditional adult-onset HD. Nonetheless, the frequent predominance of bradykinesia and dystonia early in the course of the illness, more frequent occurrence of epilepsy and myoclonus, more widespread pathology, and larger genetic lesion means that the distinction is still relevant. In addition, the relative rarity of JHD means that the clinician managing the patient is often doing so for the first time. Management is, at best, symptomatic and supportive with few or no evidence-based guidelines. In this article, the authors will review what is known of the condition and present some suggestions based on their experience.

The OEIS complex: two case reports that illustrate the spectrum of abnormalities and a review of the literature.

We present two cases of OEIS (omphalocele, exstrophy, imperforate anus, spinal defects) complex -MIM 258040 and a review of the literature. Case 1 was a 14-year-old girl who presented at 30 weeks' gestation. An ultrasound examination showed an omphalocele and spina bifida; the bladder was not visualised. She went into spontaneous labour two weeks later and the baby died shortly after birth. A full post-mortem examination was refused, but the mother did agree to an external examination, skin biopsy for fibroblast culture, X rays and MR imaging. The MR imaging showed a pelvic kidney, a large omphalocele containing the other kidney, liver, bowel and a fluid filled structure thought to represent an exstrophy of the bladder (EB). Case 2 was a 30-year-old woman who had an ultrasound examination at 20 weeks' gestation; this showed an omphalocele, but the bladder was not visualised. The pregnancy was subsequently terminated and a post-mortem examination showed a low set umbilical cord associated with a small omphalocele; there was an imperforate anus; a blind ending rectum terminated in the omphalocele. We conclude that these two cases illustrate the variability of the OEIS complex.

Subtelomeric deletions of chromosome 9q: a novel microdeletion syndrome.

Fluorescent in situ hybridization (FISH) screening of subtelomeric rearrangements has resulted in the identification of previously unrecognized chromosomal causes of mental retardation with and without dysmorphic features. This article reports the phenotypic and molecular breakpoint characterization in a cohort of 12 patients with subtelomeric deletions of chromosome 9q34. The phenotypic findings are consistent amongst these individuals and consist of mental retardation, distinct facial features and congenital heart defects (primarily conotruncal defects). Detailed breakpoint mapping by FISH, microsatellite and single nucleotide polymorphism (SNP) genotyping analysis has narrowed the commonly deleted region to an approximately 1.2 Mb interval containing 14 known transcripts. The majority of the proximal deletion breakpoints fall within a 400 kb interval between SNP markers C12020842 proximally and C80658 distally suggesting a common breakpoint in this interval.