Fragile x-associated premature ovarian failure in a large Turkish cohort: Findings of Hacettepe Fragile X Registry.

OBJECTIVE: To determine frequency of fragile X associated premature ovarian insufficiency (FXPOI) among Turkish premutation carriers. STUDY DESIGN: FMR1 premutation is the single most common genetic cause of POI (FXPOI). Fragile X Registry at Hacettepe University has been reviewed for the frequency of FXPOI among female premutation carriers. Since 1991 when FMR1 testing was available, 760 individuals from 243 families have been registered. Actual data on menstrual status of female premutation carriers were gathered and analysed. RESULTS: Among 314 premutation-bearing females in the cohort, 268 could be reached for an update of their menstrual history; 107 adults were 40 or younger and 156 were older than 40 years of age, whereas the remaining 5 patients were prepubertal. Among 263 postpubertal females with premutations, 90 women stopped menstruating before or at 40 years of age (premature ovarian failure - POF), constituting 34.2% of our cohort. Additionally, one carrier of a gray zone allele experienced FXPOI. History of twinning was present once in 18 women (5.7%) and twice in two women (0.6%), one of the latter interestingly bearing a full-mutation. CONCLUSIONS: FXPOI rates in the present cohort are higher than those reported in other populations. Higher FXPOI rates in Turkish premutation carriers might be a reflection of younger mean menopause age and higher POI rates in otherwise healthy Turkish women. Since POI is much more frequent among premutation carriers than in general population, testing for CGG repeat expansions in FMR1 should be included in the work-up.

Methylene tetrahydrofolate reductase polymorphisms and homocysteine level in heart defects.

BACKGROUND: While several single nucleotide polymorphisms are known to influence the metabolism of folate, the methylene tetrahydrofolate reductase (MTHFR) gene has been the most extensively studied. The aim of this study was to investigate the relationship between the MTHFR polymorphisms 1298A>C and 677C>T and congenital heart disease. In addition, the relationship between these gene polymorphisms and homocysteine level was determined in Turkish subjects. METHODS: Patients with non-syndromic congenital heart defects who were admitted to the Pediatric Cardiology Unit at Hacettepe University Ihsan Dogramaci Children's Hospital, Ankara, Turkey between June 2002 and June 2003 were recruited for the study. A total of 163 children with congenital heart defects (mean age, 7.63 ± 6.03 years; M/F, 93/70) and 93 healthy controls were analyzed. RESULTS: When evaluated either separately or together, there were no differences in the frequency of MTHFR 677C>T or 1298A>C polymorphisms between the children with congenital heart defects and the control group. The results were the same when considering only conotruncal defects. Those with the 677C>T polymorphism had significantly lower homocysteine level (P = 0.004), but the 1298A>C polymorphism was not related to homocysteine level. CONCLUSION: No relationship was found between congenital heart defects and 1298A>C or 677C>T polymorphisms. The 677C>T polymorphism was related to low homocysteine level. Because there is often much heterogeneity between populations, this study should be conducted in different populations and with larger numbers of participants.

Derivative chromosome 1 and GLUT1 deficiency syndrome in a sibling pair.

BACKGROUND: Genomic imbalances constitute a major cause of congenital and developmental abnormalities. GLUT1 deficiency syndrome is caused by various de novo mutations in the facilitated human glucose transporter 1 gene (1p34.2) and patients with this syndrome have been diagnosed with hypoglycorrhachia, mental and developmental delay, microcephaly and seizures. Furthermore, 1q terminal deletions have been submitted in the recent reports and the absence of corpus callosum has been related to the deletion between C1orf100 and C1orf121 in 1q44. RESULTS: This study reports on a sibling pair with developmental delay, mental retardation, microcephaly, hypotonia, epilepsy, facial dysmorphism, ataxia and impaired speech. Chromosome analysis revealed a derivative chromosome 1 in both patients. FISH and MCB analysis showed two interstitial deletions at 1p34.2 and 1q44. SNP array and array-CGH analysis also determined the sizes of deletions detailed. The deleted region on 1p34.2 encompasses 33 genes, among which is GLUT1 gene (SLC2A1). However, the deleted region on 1q44 includes 59 genes and distal-proximal breakpoints were located in the ZNF672 gene and SMYD3 gene, respectively. CONCLUSION: Haploinsufficiency of GLUT1 leads to GLUT1 deficiency syndrome, consistent with the phenotype in patients of this study. Conversely, in the deleted region on 1q44, none of the genes are related to findings in these patients. Additionally, the results confirm previous reports on that corpus callosal development may depend on the critical gene(s) lying in 1q44 proximal to the SMYD3 gene.

Mutations in the gene encoding the RER protein FKBP65 cause autosomal-recessive osteogenesis imperfecta.

Osteogenesis imperfecta is a clinically and genetically heterogeneous brittle bone disorder that results from defects in the synthesis, structure, or posttranslational modification of type I procollagen. Dominant forms of OI result from mutations in COL1A1 or COL1A2, which encode the chains of the type I procollagen heterotrimer. The mildest form of OI typically results from diminished synthesis of structurally normal type I procollagen, whereas moderately severe to lethal forms of OI usually result from structural defects in one of the type I procollagen chains. Recessively inherited OI, usually phenotypically severe, has recently been shown to result from defects in the prolyl-3-hydroxylase complex that lead to the absence of a single 3-hydroxyproline at residue 986 of the alpha1(I) triple helical domain. We studied a cohort of five consanguineous Turkish families, originating from the Black Sea region of Turkey, with moderately severe recessively inherited OI and identified a novel locus for OI on chromosome 17. In these families, and in a Mexican-American family, homozygosity for mutations in FKBP10, which encodes FKBP65, a chaperone that participates in type I procollagen folding, was identified. Further, we determined that FKBP10 mutations affect type I procollagen secretion. These findings identify a previously unrecognized mechanism in the pathogenesis of OI.

Subtelomeric rearrangements in mental retardation: Hacettepe University experience in 130 patients.

Recent reports have revealed the presence of subtelomeric rearrangements in 0.5-1.1% of patients with mild mental retardation and in 6.8-7.4% of patients with moderate-severe mental retardation. In the present study, 130 patients with unexplained mental retardation were tested using fluorescence in situ hybridization (FISH) analysis for the first time in a large group of Turkish patients, in order to determine the frequency of subtelomeric rearrangements. Three patients had such rearrangements. We present the clinical findings in these patients with (1) coexistent 9p subtelomeric monosomy and 4q subtelomeric trisomy, (2) 22q13.3 subtelomeric monosomy, and (3) coexistent 4p subtelomeric monosomy and 8p subtelomeric trisomy. Mild retardation without dysmorphic features in one of these patients suggests offering subtelomeric analysis to a wide spectrum of mental retardation.

Clinically abnormal case with paternally derived partial trisomy 8p23.3 to 8p12 including maternal isodisomy of 8p23.3: a case report.

BACKGROUND: Because of low copy repeats (LCRs) and common inversion polymorphisms, the human chromosome 8p is prone to a number of recurrent rearrangements. Each of these rearrangements is associated with several phenotypic features. We report on a patient with various clinical malformations and developmental delay in connection with an inverted duplication event, involving chromosome 8p. METHODS: Chromosome analysis, multicolor banding analysis (MCB), extensive fluorescence in situ hybridization (FISH) analysis and microsatellite analysis were performed. RESULTS: The karyotype was characterized in detail by multicolor banding (MCB), subtelomeric and centromere-near probes as 46,XY,dup(8)(pter->p23.3::p12->p23.3::p23.3->qter). Additionally, microsatellite analysis revealed the paternal origin of the duplication and gave hints for a mitotic recombination involving about 6 MB in 8p23.3. CONCLUSION: A comprehensive analysis of the derivative chromosome 8 suggested a previously unreported mechanism of formation, which included an early mitotic aberration leading to maternal isodisomy, followed by an inverted duplication of the 8p12p23.3 region.

Pseudo-trisomy 13 in a fetus: further support for autosomal recessive inheritance.

Pseudo-trisomy 13 is defined in chromosomally normal patients with holoprosencephaly and associating features suggestive of trisomy 13. An autosomal recessive pattern of inheritance for this situation is most likely, but a gene for this condition has not yet been mapped. A fetus is presented with phenotypic features reminiscent of trisomy 13 but a normal karyotype, 46, XY. The pregnancy was terminated due to severe fetal malformations. In autopsy, the fetus had semilobar holoprosencephaly, hydrocephaly and dysmorphic features such as hypotelorism, cleft lip, a flat nose with a single nostril, low-set ears, postaxial polydactyly in all extremities, left unilateral pes equinovarus and pulmonary segmentation defect on the right. The parents were 2nd cousins once removed. Holoprosencephaly and polydactyly with or without other findings in chromosomally normal patients should raise the suspicion of pseudo-trisomy 13 syndrome, particularly when parental consanguinity is present.

Cryptic trisomy 5q35.2qter and deletion 1p36.3 characterised using FISH and array-based CGH.

A 10(6/12)-year-old boy was referred to the genetics department because of mental retardation and dysmorphic findings including microcephaly, flat face, down-slanting palpebral fissures, strabismus, prominent ears, bulbous nasal tip, down-turned corners of the mouth, narrow palate, clinodactyly of the fifth fingers and generalised eczema. Cytogenetic analysis revealed a karyotype of 47,XY,+mar of paternal origin. Multicolour FISH showed the marker chromosome to be derived from chromosome 15. For further elucidation of the phenotype, array-based comparative genomic hybridisation (aCGH) was performed, which revealed dup(5)(q35.2qter) and del(1)(p36.3). Parental FISH analysis revealed that the translocation occurred de novo. Despite the presence of a clinical phenotype along with a microscopically visible chromosomal aberration, a complex cryptic cytogenetic abnormality was causative for the phenotype of the patient. Elucidation of this complex aberration required combination of the whole cytogenetic toolbox.

CYP1A1 gene polymorphism and polycystic ovary syndrome.

The aim of this study was to assess the rates of variant alleles of cytochrome P4501A1 (CYP1A1) in patients with polycystic ovary syndrome (PCOS). It was designed as a case-control study in Hacettepe University, Faculty of Medicine, Department of Obstetrics and Gynecology and Genetics. Forty-eight patients with PCOS served as the study group. Ninety-six regularly cycling women with no clinical and biochemical evidence of hyperandrogenism and polycystic ovary appearance served as the controls. The CYP1A1 variant alleles of all patients were determined via polymerase chain reaction. The rate of the CYP1A1 isoleucine (Ile)/valine (Val) allele was significantly higher in patients with PCOS than in the controls (OR: 7.8, 95% CI: 3.45-17.52, P < 0.001). However, there was no statistically significant difference in the distribution of Val/Val genotype (OR: 4.0, 95% CI: 0.60-26.73). The rate of any Val genotype (Ile/Val or Val/Val) was significantly higher in patients with PCOS compared with the control group (OR: 7.4, 95% CI: 3.33-16.46, P < 0.001). In conclusion, the patients with PCOS had a 7.8-fold higher frequency of CYP1A1 Ile/Val genotype and a 7.4-fold higher frequency of CYP1A1 of any Val genotype (Ile/Val or Val/Val).

Factor V Leiden mutation and type 1 diabetes mellitus.

Diabetes mellitus is considered to cause a tendency for arterial thrombosis. Recent studies addressed the association between venous and arterial disease. Resistance to activated protein C is one of the most common causes of venous thrombosis and linked to a single point mutation in the factor V gene, designated as factor V Leiden mutation. There is little information regarding the status of factor V Leiden mutation in type 1 diabetes. The aim of this study is to evaluate association among activated protein C sensitivity ratio, factor V Leiden mutation, and type 1 diabetes taking into account metabolic control, lipids and diabetic complications. The study population consisted of 47 healthy subjects (27.9 +/- 1.2 years) and 48 type 1 diabetic patients (27.9 +/- 1.1 years). Activated protein C sensitivity ratio was measured by activated partial thromboplastin time based assay. The presence of factor V Leiden mutation was determined by amplifying the fragments encompassing gene mutation by PCR. Mean normalized activated protein C sensitivity ratio values and prevalence of heterozygous factor V Leiden mutation were not significantly different between groups (1.08 +/- 0.03 and 6.3% in healthy subjects; 1.01 +/- 0.03 and 6.4% in type 1 diabetic patients, respectively). The activated protein C sensitivity ratio and factor V Leiden mutation were not found to be linked with metabolic control parameters, lipids and diabetic complications in type 1 diabetic patients. There was no association among factor V Leiden mutation, activated protein C sensitivity ratio and type 1 diabetes, metabolic control parameters as well as complications of diabetes. Although the propensity to thrombosis is increased in individuals with type 1 diabetes, activated protein C sensitivity ratio and factor V Leiden mutation do not appear to be significant determinants.

Cerebro-facio-thoracic dysplasia: expanding the phenotype.

We report a further two patients with cerebro-facio-thoracic dysplasia, a rare autosomal recessive condition with thoracic costovertebral dysplasia, developmental delay and characteristic facial features. One of our patients has the additional features of large, bilateral colobomas of the optic nerve, ptosis, small conical teeth and severe left-sided talipes. He also has hypermobile joints, especially in his hands and anterior subluxation of the shoulders. The second patient has hypodensity of the grey matter on magnetic resonance imaging, which is the second report of this finding in cerebro-facio-thoracic dysplasia. In addition, he has hypoplasia of the corpus callosum. These cases illustrate the expanding phenotype of this condition, and support the hypothesis that this is an autosomal recessive condition.

Application of medical genetics in Turkey.

Turkey is among the most populous countries of the world, and has a young population structure. The rate of consanguinity has been approximately 20-25% for the last 25 years. Various studies have shown that high consanguinity can be a contributing factor to the high incidence of some rare autosomal recessive diseases. Hemoglobinopathies are an important health problem, and Turkey also has one of the highest incidences of phenylketonuria in the world. Training and education in medical genetics, established as a specialty since 1972, play an important role in the setting of genetic services and meeting public health problems. Prenatal and preimplantation diagnosis is available for a variety of fetal diseases.

Myelodysplastic syndrome associated with monosomy 7 in childhood: a retrospective study.

Myelodysplastic syndrome (MDS) is a clonal hematopoietic stem cell disorder characterized by ineffective hematopoiesis, peripheral cytopenia, and dysplastic changes in the bone marrow. Monosomy 7 or partial loss of 7q is a common cytogenetic abnormality in MDS patients and is associated with poor prognosis. This study examined eight patients with monosomy 7 and MDS. Five MDS patients with monosomy 7 progressed to acute leukemia: three cases transformed into acute myelogenous leukemia (AML) in a mean time of only 4.6 months and two cases into acute lymphoblastic leukemia (ALL) in a mean time of 9 months. To our knowledge, this is the first report showing progression of monosomy 7 associated with MDS to ALL in the childhood period.

Congenital contractural arachnodactyly (Beals syndrome).

Congenital contractural arachnodactyly (Beals syndrome) is an autosomal dominantly inherited connective tissue disorder characterized by multiple flexion contractures, arachnodactyly, severe kyphoscoliosis, abnormal pinnae and muscular hypoplasia. It is caused by a mutation in FBN2 gene on chromosome 5q23. Although the clinical features can be similar to Marfan syndrome (MFS), multiple joint contractures (especially elbow, knee and finger joints), and crumpled ears in the absence of significant aortic root dilatation are characteristic of Beals syndrome and rarely found in Marfan syndrome. The incidence of CCA is unknown and its prevalence is difficult to estimate considering the overlap in phenotype with MFS; the number of patients reported has increased following the identification of FBN2 mutation. Molecular prenatal diagnosis is possible. Ultrasound imaging may be used to demonstrate joint contractures and hypokinesia in suspected cases. Management of children with CCA is symptomatic. Spontaneous improvement in camptodactyly and contractures is observed but residual camptodactyly always remains. Early intervention for scoliosis can prevent morbidity later in life. Cardiac evaluation and ophthalmologic evaluations are recommended.

Terminal phalangeal accessory ossification center of the thumb: an additional radiographic finding in Larsen syndrome.

Larsen syndrome is an autosomal-dominant disorder characterized by multiple joint dislocations, vertebral anomalies and dysmorphic facies. Both autosomal-dominant and autosomal-recessive forms of the disorder have been proposed. Individuals with autosomal-dominant Larsen syndrome have characteristic "cylindrical-shape" thumbs caused by broad, shortened phalanges. Autosomal-dominant Larsen syndrome results from heterozygosity for mutations in filamin B, a cytoskeletal protein involved in multicellular processes. We report here a patient with a duplicated or accessory distal thumb phalanx and multiple large joint dislocations who was shown to be heterozygous for a filamin B mutation predicting the amino acid substitution G1691S. This adds a new radiographic finding, duplicated or accessory distal phalanx, to the radiographic abnormalities seen in this rare dominant disorder.

Isodicentric Y (p11.32) chromosome in an infant with mixed gonadal dysgenesis.

Among the structural abnormalities affecting the human Y chromosome, dicentric chromosomes are the most common. A wide spectrum of phenotypes of patients with a dicentric Y chromosome exists, ranging from almost males through mixed gonadal dysgenesis to females with Turner syndrome. Here, we describe an infant with mixed gonadal dysgenesis and mosaic karyotype 45,X/46,X,idic(Y)(qter-->p11.32:p11.32-->qter)/47,X,+2idic(Y) (qter-->p11.32:p11.32-->qter)/47,XYY. This was demonstrated by fluorescence in situ hybridization (FISH) analysis with whole Y chromosome painting (WCP-Y) probe. Molecular studies were performed on genomic DNA extracted from peripheral blood lymphocytes. To examine the sex determined region (SRY), azoospermia factor (AZF) region and deletion in azoospermia gene (DAZ), polymerase chain reaction (PCR) analyses were done with sequence-tagged site (STS) primers of 20 loci along the Y chromosome (SRY, DYS271, DYS148, DYS273, KALY, DYS212, SMCY, DYS215, DYS218, DYS219, DYS221, DYS223, DYS224, DYF51S1, DYS236, DAZ, DYS240), and all tested loci were found positive. Because of the possibility of a mutation in the SRY gene, we analyzed the PCR fragment by DNA sequencing and did not observe any mutation or nucleotide alteration. We present detailed molecular-cytogenetic characterization of a patient with idic(Y)(p11.32), and results are discussed with the previously described patients. As far as we know, this is the fifth report of a 46,X, idic(Y)(p11.32) karyotype and the first presentation with mixed gonadal dysgenesis and isodicentric Y. Since the correlation between phenotype and karyotype is not yet well defined, the clinical reports will be helpful in defining the phenotypic range of this chromosomal abnormality.

Central precocious puberty in a girl with Williams syndrome: the result of treatment with GnRH analogue.

Williams syndrome (WS) is a well-known microdeletion syndrome characterized by specific facial features, retardation in growth and development, typical personality and cardiac defects. Poor growth potential is further affected by central precocious puberty (CPP) which is frequent in these patients. A WS patient with CPP is presented, whose pubertal development and bone age progression were arrested by administration of GnRH analogues. The case is reported to discuss the role of GnRH analogues for management of CPP in patients with WS.