Novel THAP1 sequence variants in primary dystonia.

BACKGROUND: THAP1 encodes a transcription factor (THAP1) that harbors an atypical zinc finger domain and regulates cell proliferation. An exon 2 insertion/deletion frameshift mutation in THAP1 is responsible for DYT6 dystonia in Amish-Mennonites. Subsequent screening efforts in familial, mainly early-onset, primary dystonia identified additional THAP1 sequence variants in non-Amish subjects. OBJECTIVE: To examine a large cohort of subjects with mainly adult-onset primary dystonia for sequence variants in THAP1. METHODS: With high-resolution melting, all 3 THAP1 exons were screened for sequence variants in 1,114 subjects with mainly adult-onset primary dystonia, 96 with unclassified dystonia, and 600 controls (400 neurologically normal and 200 with Parkinson disease). In addition, all 3 THAP1 exons were sequenced in 200 subjects with dystonia and 200 neurologically normal controls. RESULTS: Nine unique melting curves were found in 19 subjects from 16 families with primary dystonia and 1 control. Age at dystonia onset ranged from 8 to 69 years (mean 48 years). Sequencing identified 6 novel missense mutations in conserved regions of THAP1 (G9C [cervical, masticatory, arm], D17G [cervical], F132S [laryngeal], I149T [cervical and generalized], A166T [laryngeal], and Q187K [cervical]). One subject with blepharospasm and another with laryngeal dystonia harbored a c.-42C>T variant. A c.57C>T silent variant was found in 1 subject with segmental craniocervical dystonia. An intron 1 variant (c.71+9C>A) was present in 7 subjects with dystonia (7/1,210) but only 1 control (1/600). CONCLUSIONS: A heterogeneous collection of THAP1 sequence variants is associated with varied anatomical distributions and onset ages of both familial and sporadic primary dystonia.

In cis autosomal dominant mutation of Senataxin associated with tremor/ataxia syndrome.

Senataxin mutations are the molecular basis of two distinct syndromes: (1) ataxia oculomotor apraxia type 2 (AOA2) and (2) juvenile amyotrophic lateral sclerosis 4 (ALS4). The authors describe clinical and molecular genetic studies of mother and daughter who display symptoms of cerebellar ataxia/atrophy, oculomotor defects, and tremor. Both patients share Senataxin mutations N603D and Q653K in cis (N603D-Q653K), adjacent to an N-terminal domain thought to function in protein-protein interaction. The N-terminal and helicase domains appear to harbor missense mutation clusters associated with AOA2 and ALS4. Working synergistically, the N603D-Q653K mutations may confer a partial dominant negative effect, acting on the senataxin N-terminal, further expanding the phenotypic spectrum associated with Senataxin mutations.

Evaluation of growth and hormonal status in patients referred to the International Fanconi Anemia Registry.

OBJECTIVES: 1) To determine the extent of short stature in patients with Fanconi anemia (FA); 2) to determine the extent and nature of endocrinopathy in FA; 3) to assess the impact on height of any endocrinopathies in these patients; and 4) to study the correlation, if any, between height, endocrinopathy, and FA complementation group. STUDY DESIGN: Fifty-four patients with FA, 30 males and 24 females from 47 unrelated families, were prospectively evaluated in a Pediatric Clinical Research Center. The patients ranged in age from 0.1-31.9 years, with the mean age at assessment 8.6 years. RESULTS: Endocrine abnormalities were found in 44 of the 54 FA patients tested (81%), including short stature, growth hormone (GH) insufficiency, hypothyroidism, glucose intolerance, hyperinsulinism, and/or overt diabetes mellitus. Twenty-one of 48 (44%) participants had a subnormal response to GH stimulation; 19 of 53 (36%) had overt or compensated hypothyroidism, while 8 of 40 participants had reduced thyroid-hormone binding. Two patients were diabetic at the time of study; impaired glucose tolerance was found in 8 of 40 patients (25%), but most surprisingly, hyperinsulinemia was present in 28 of 39 (72%) participants tested. Significantly, spontaneous overnight GH secretion was abnormal in all patients tested (n = 13). In addition, participants demonstrated a tendency toward primary hypothyroidism with serum tetraiodothyronine levels at the lower range of normal, while also having thyrotropin (thyroid-stimulating hormone) levels at the high end of normal. Sixteen patients were assigned to FA complementation group A, (FA-A), 12 to FA-C, and 5 to FA-G; 10 of the 12 participants in FA-C were homozygous for a mutation in the intron-4 donor splice site of the FANCC gene. Patients in groups FA-A and FA-G were relatively taller than the group as a whole (but still below the mean for the general population), whereas those in FA-C had a significantly reduced height for age. GH response to stimulation testing was most consistently normal in participants from FA-G, but this did not reach statistical significance. The tendency toward hypothyroidism was more pronounced in participants belonging to complementation groups FA-C and FA-G, whereas insulin resistance was most evident in patients in FA-G, and least evident in those in FA-C. Short stature was a very common finding among the patients with a mean height >2 standard deviations below the reference mean (standard deviation score: -2.35 +/- 0.28). Patients with subnormal GH response and those with overt or compensated hypothyroidism were shorter than the group with no endocrinopathies. The heights of those participants with glucose or insulin abnormalities were less severely affected than those of normoglycemic, normoinsulinemic participants, although all were significantly below the normal mean. The mean height standard deviation score of patients with entirely normal endocrine function was also >2 standard deviations below the normal mean, demonstrating that short stature is an inherent feature of FA. CONCLUSION: Endocrinopathies are a common feature of FA, primarily manifesting as glucose/insulin abnormalities, GH insufficiency, and hypothyroidism. Although short stature is a well-recognized feature of FA, 23 patients (43%) were within 2 standard deviations, and 5 of these (9% of the total) were actually above the mean for height for the general population. Those patients with endocrine dysfunction are more likely to have short stature. These data indicate that short stature is an integral feature of FA, but that superimposed endocrinopathies further impact on growth. The demonstration of abnormal endogenous GH secretion may demonstrate an underlying hypothalamic-pituitary dysfunction that results in poor growth.

Somatic mosaicism in Fanconi anemia: evidence of genotypic reversion in lymphohematopoietic stem cells.

Somatic mosaicism has been observed previously in the lymphocyte population of patients with Fanconi anemia (FA). To identify the cellular origin of the genotypic reversion, we examined each lymphohematopoietic and stromal cell lineage in an FA patient with a 2815-2816ins19 mutation in FANCA and known lymphocyte somatic mosaicism. DNA extracted from individually plucked peripheral blood T cell colonies and marrow colony-forming unit granulocyte-macrophage and burst-forming unit erythroid cells revealed absence of the maternal FANCA exon 29 mutation in 74.0%, 80.3%, and 86.2% of colonies, respectively. These data, together with the absence of the FANCA exon 29 mutation in Epstein-Barr virus-transformed B cells and its presence in fibroblasts, indicate that genotypic reversion, most likely because of back mutation, originated in a lymphohematopoietic stem cell and not solely in a lymphocyte population. Contrary to a predicted increase in marrow cellularity resulting from reversion in a hematopoietic stem cell, pancytopenia was progressive. Additional evaluations revealed a partial deletion of 11q in 3 of 20 bone marrow metaphase cells. By using interphase fluorescence in situ hybridization with an MLL gene probe mapped to band 11q23 to identify colony-forming unit granulocyte-macrophage and burst-forming unit erythroid cells with the 11q deletion, the abnormal clone was exclusive to colonies with the FANCA exon 29 mutation. Thus, we demonstrate the spontaneous genotypic reversion in a lymphohematopoietic stem cell. The subsequent development of a clonal cytogenetic abnormality in nonrevertant cells suggests that ex vivo correction of hematopoietic stem cells by gene transfer may not be sufficient for providing life-long stable hematopoiesis in patients with FA.

Understanding the intention to permanently follow a high folate diet among a sample of low-income pregnant women according to the Health Belief Model.

Despite folate fortification of the US food supply beginning January 1, 1998, evidence indicates that a substantial proportion of women of child-bearing age will continue to have folate intakes inadequate for the prevention of neural tube defects (NTDs). Therefore, health education remains an essential component of this public health campaign. The purpose of this study was to determine the applicability of the Health Belief Model (HBM) to understanding the intention to permanently follow a high folate diet among low-income pregnant women. A convenience sample of 251 low-income pregnant women participated in individual 15 min interviews assessing their folate attitudes and beliefs according to the model. Correlations consistent with the HBM were found between the perceived susceptibility, perceived severity, perceived benefits, perceived barriers, self-efficacy and cues to action constructs, and participants' intention to permanently follow a high folate diet (folate intention). In regression analyses, the perceived benefits construct was consistently the most predictive of folate intention. Participants were generally unfamiliar with and had many misperceptions concerning both folate and NTDs. The HBM may offer an effective foundation for development of tailored educational interventions promoting permanent consumption of a high folate diet among low-income women.

Sequence variation in the Fanconi anemia gene FAA.

Fanconi anemia (FA) is a genetically heterogeneous autosomal recessive syndrome associated with chromosomal instability, hypersensitivity to DNA crosslinking agents, and predisposition to malignancy. The gene for FA complementation group A (FAA) recently has been cloned. The cDNA is predicted to encode a polypeptide of 1,455 amino acids, with no homologies to any known protein that might suggest a function for FAA. We have used single-strand conformational polymorphism analysis to screen genomic DNA from a panel of 97 racially and ethnically diverse FA patients from the International Fanconi Anemia Registry for mutations in the FAA gene. A total of 85 variant bands were detected. Forty-five of the variants are probably benign polymorphisms, of which nine are common and can be used for various applications, including mapping studies for other genes in this region of chromosome 16q. Amplification refractory mutation system assays were developed to simplify their detection. Forty variants are likely to be pathogenic mutations. Seventeen of these are microdeletions/microinsertions associated with short direct repeats or homonucleotide tracts, a type of mutation thought to be generated by a mechanism of slipped-strand mispairing during DNA replication. A screening of 350 FA probands from the International Fanconi Anemia Registry for two of these deletions (1115-1118del and 3788-3790del) revealed that they are carried on about 2% and 5% of the FA alleles, respectively. 3788-3790del appears in a variety of ethnic groups and is found on at least two different haplotypes. We suggest that FAA is hypermutable, and that slipped-strand mispairing, a mutational mechanism recognized as important for the generation of germ-line and somatic mutations in a variety of cancer-related genes, including p53, APC, RB1, WT1, and BRCA1, may be a major mechanism for FAA mutagenesis.

Phenotypic consequences of mutations in the Fanconi anemia FAC gene: an International Fanconi Anemia Registry study.

Fanconi anemia (FA) is a genetically and phenotypically heterogeneous disorder defined by cellular hypersensitivity to DNA cross-linking agents; mutations in the gene defective in FA complementation group C, FAC, are responsible for the syndrome in a subset of patients. We have performed an analysis of the clinical effects of specific mutations in the FAC gene. Using the amplification refractory mutation system assays that we developed to rapidly detect FAC mutations, at least one mutated copy of the FAC gene was identified in 59 FA patients from the International Fanconi Anemia Registry (IFAR). This represents 15% of the 397 FA patients tested. FA-C patients were divided into three subgroups based on results of a genotype-phenotype analysis using the Cox proportional hazards model: (1) patients with the IVS4 mutation (n = 26); (2) patients with at least one exon 14 mutation (R548X or L554P) (n = 16); and (3) patients with at least one exon 1 mutation (322delG or Q13X) and no known exon 14 mutation (n = 17). Kaplan-Meier analysis shows that IVS4 or exon 14 mutations define poor risk subgroups, as they are associated with significantly earlier onset of hematologic abnormalities and poorer survival compared to exon 1 patients and to the non-FA-C IFAR population. There was no direct correlation between the degree of cellular hypersensitivity to the clastogenic effect of diepoxybutane and severity of clinical phenotype. Sixteen of the 59 FA-C patients (27%) have developed acute myelogenous leukemia. Thirteen of these patients have died; AML was the cause of death in 46% of the expired FA-C patients. This study enables us to define this clinically heterogeneous disorder genotypically to better predict clinical outcome and aid decision-making regarding major therapeutic modalities for a subset of FA patients.

Centromeric alphoid DNA heteromorphisms of chromosome 21 revealed by FISH-technique.

The centromeric heterochromatin of chromosome 21 has been evaluated by the fluorescence in situ hybridization (FISH) technique. It was found that the alphoid DNA sequences of pericentromeric regions of chromosome 21 were highly heteromorphic when a centromeric specific probe was hybridized to these sequences. The variations were so extreme that they could even be arbitrarily classified into at least five sizes by comparison with the length of the short arm (p) of chromosome 18. They are negative (1); small (2); medium (3); large (4); and very large (5). We used 15 normal cases and 12 individuals with trisomy 21 (Down syndrome), and the incidences for these five classes were 3.0%, 22.7%, 59.2%, 13.6% and 1.5%, respectively. At least 3% of the chromosomes no. 21 did not show any trace of hybridization signals, which apparently escape detection at interphase level as well. Although, the variations observed in the present study are continuous, the proposed classification may yield some implications for future investigations.

A neglected lesbian health concern: cervical neoplasia.

Many health care providers believe that lesbian women do not need routine Papanicolaou smears. This erroneous assumption fails to recognize that the majority of lesbian women have had prior heterosexual relationships and thus may be at risk for developing cervical neoplasia. The following case report describes a lesbian woman who denied prior heterosexual intercourse but who developed cervical intraepithelial neoplasia grade 2 (CIN 2) associated with a high oncogenic risk human papillomavirus (HPV) type. Sexual contact with multiple lesbian partners who had previous heterosexual relationships likely explains her cervical disease.