Genome-wide compound heterozygote analysis highlights alleles associated with adult height in Europeans.

Adult height is the most widely genetically studied common trait in humans; however, the trait variance explainable by currently known height-associated single nucleotide polymorphisms (SNPs) identified from the previous genome-wide association studies (GWAS) is yet far from complete given the high heritability of this complex trait. To exam if compound heterozygotes (CH) may explain extra height variance, we conducted a genome-wide analysis to screen for CH in association with adult height in 10,631 Dutch Europeans enriched with extremely tall people, using our recently developed method implemented in the software package CollapsABEL. The analysis identified six regions (3q23, 5q35.1, 6p21.31, 6p21.33, 7q21.2, and 9p24.3), where multiple pairs of SNPs as CH showed genome-wide significant association with height (P < 1.67 × 10-10). Of those, 9p24.3 represents a novel region influencing adult height, whereas the others have been highlighted in the previous GWAS on height based on analysis of individual SNPs. A replication analysis in 4080 Australians of European ancestry confirmed the significant CH-like association at 9p24.3 (P < 0.05). Together, the collapsed genotypes at these six loci explained 2.51% of the height variance (after adjusting for sex and age), compared with 3.23% explained by the 14 top-associated SNPs at 14 loci identified by traditional GWAS in the same data set (P < 5 × 10-8). Overall, our study empirically demonstrates that CH plays an important role in adult height and may explain a proportion of its "missing heritability". Moreover, our findings raise promising expectations for other highly polygenic complex traits to explain missing heritability identifiable through CH-like associations.

Clinical presentation and molecular genetic analysis of a Sudanese family with a novel mutation in the CYP2R1 gene.

The aim of this study was to identify the genetic basis of two female siblings - born to consanguineous Sudanese parents - diagnosed clinically as having the rare condition of 25-hydroxylase deficiency (vitamin D-dependent rickets type 1B). The initial diagnosis was established based on clinical data, laboratory and radiological findings retrospectively. Primers for all exons (5) of human CYP2R1 (NM_024514) were generated followed by Sanger sequencing on exons 1-5 for both girls and their parents. Homozygosity for a point mutation (c.85C > T) was detected, leading to a nonsynonymous variant at position 29 in exon 1, resulting in a premature stop codon (p.Q29X). This is a previously unknown variant that leads to a severely truncated protein and predicted to be among the 0.1 % most deleterious genomic variants(CADD score 36). To our knowledge, this family represents the first case series from Sudan with a confirmed CYP2R1 gene mutation and the 6th world-wide. With the lack of genetic facilities, diagnosis should be suspected by the persistently low 25 hydroxyvitamin D level in spite of proper treatment and after ruling out liver disease and malabsorption. Patients in this case series showed healing of rickets when treated with high doses of 1,25-dihydroxyvitamin D3 (1,25(OH)D3; calcitriol) and oral calcium.

The results of CHD7 analysis in clinically well-characterized patients with Kallmann syndrome.

CONTEXT: Kallmann syndrome (KS) and CHARGE syndrome are rare heritable disorders in which anosmia and hypogonadotropic hypogonadism co-occur. KS is genetically heterogeneous, and there are at least eight genes involved in its pathogenesis, whereas CHARGE syndrome is caused by autosomal dominant mutations in only one gene, the CHD7 gene. Two independent studies showed that CHD7 mutations can also be found in a minority of KS patients. OBJECTIVE: We aimed to investigate whether CHD7 mutations can give rise to isolated KS or whether additional features of CHARGE syndrome always occur. DESIGN: We performed CHD7 analysis in a cohort of 36 clinically well-characterized Dutch patients with KS but without mutations in KAL1 and with known status for the KS genes with incomplete penetrance, FGFR1, PROK2, PROKR2, and FGF8. RESULTS: We identified three heterozygous CHD7 mutations. The CHD7-positive patients were carefully reexamined and were all found to have additional features of CHARGE syndrome. CONCLUSION: The yield of CHD7 analysis in patients with isolated KS seems very low but increases when additional CHARGE features are present. Therefore, we recommend performing CHD7 analysis in KS patients who have at least two additional CHARGE features or semicircular canal anomalies. Identifying a CHD7 mutation has important clinical implications for the surveillance and genetic counseling of patients.

Disorders of sex development: update on the genetic background, terminology and risk for the development of germ cell tumors.

BACKGROUND: Considerable progress has been made on genetic mechanisms involved in disorders of sex development and on tumor formation in dysgenetic gonads. Clinical and psychological outcome of patients are, as far as evaluated, unsatisfactory at present. Guidelines are emerging in order to optimize long-term outcome in the future. DATA SOURCES: The information obtained in this review is based on recent original publications and on the experience of our multidisciplinary clinical and research group. RESULTS: This review offers an update on our knowledge concerning gene mutations involving in disorders of sex development, on the renewed nomenclature and classification system, and on the mechanisms of tumor development in patients. CONCLUSIONS: The consensus meeting on disorders of sex development has renewed our interest in clinical studies and long-term outcome of patients. Psychological research emphasizes the importance to consider male gender identity wherever possible in cases of severe undervirilization. Patient advocacy groups demand a more conservative approach regarding gonadectomy. Medical doctors, scientists and governmental instances are increasingly interested in the set-up of international research collaborations. As a consequence, it is expected that new guidelines for the optimal care of patients will be proposed in the coming years.

Psychosocial functioning after discontinuation of long-term growth hormone treatment in girls with Turner syndrome.

It is common practice in the case of Turner syndrome (TS) to treat short stature with GH treatment and to induce puberty with estrogens at an age as close to normal puberty as possible. This approach in most cases leads to a height in the normal range in childhood, adolescence, and adulthood in TS. Little data is available, however, on its effect on psychosocial functioning. In the present study, we evaluated psychosocial functioning in a group of 50 women with TS, after reaching final height in two multicenter GH trials. Thirty-six girls participated in a randomized dose-response study from mean (SEM) age 6.8 (0.4) years, and 14 girls participated in a frequency-response study from age 13.2 (0.4) years. After discontinuation of long-term GH treatment, these 50 girls were evaluated for psychosocial functioning at a mean age of 18.8 (0.3) years. GH was given in a dosage of 4 IU/m2/day (approximately 0.045 mg/kg/day), 6 IU/m2/day, or 8 IU/m2/day. After a mean GH treatment duration of 7.1 (0.4) years, mean final height (ref. normal girls) was FH1.2 (0.2) SD score. Behavioral problem scores (Achenbach) of the TS women were comparable to normal Dutch peers. Although self-perception (Harter total scale: p < 0.01), and bodily attitude (Baardman: p < 0.05) was significantly less positive than for their normal Dutch peers, we found no evidence of depression. TS women rated their family functioning higher than their Dutch peers (p < 0.0001), and had a slightly different coping pattern. These results show that even after reaching a height in most cases within the normal range and puberty induction at a pubertal age, some women with TS still experience psychosocial problems. It is likely, however, that GH and estrogen treatment improved psychosocial functioning. Long-term follow-up of these GH-treated patients will allow an evaluation of their life achievements.

Familial gigantism caused by an NSD1 mutation.

A three-generation family with autosomal dominant segregation of a novel NSD1 mutation (6605G --> A, resulting in Cys2202Tyr) is reported. Haploinsufficiency of NSD1 has been identified as the major cause of Sotos syndrome. The overgrowth condition (MIM 117550) is characterized by facial anomalies, macrocephaly, advanced bone age, and learning disabilities. Manifestations in the present family include dramatically increased height, weight, and head circumference together with a long face, large mandible, and large ears, but mental deficiency was absent.