Diagnosis of Fanconi's Anemia by Diepoxybutane Analysis in Children from Serbia.

The high sensitivity of Fanconi's anemia (FA) cells to drug induced DNA interstrand crosslinks (ICL) such as diepoxybutane (DEB) was used as a part of FA screening in the children with clinical suspicion of FA. The study considered a total of 66 children with the hematological and/or congenital phenotypic symptoms reminiscent of FA. Blood samples from patients with clinical suspicion of FA and controls were collected for chromosome fragility evaluation by the DEB test. According to the results of DEB test, the patients were divided into two subgroups: FA displaying typical DEB sensitive cellular response and non FA. In this study, 10 out of 66 patients were found to have a FA cellular phenotype. The percentage of DEB-induced aberrant cells was increased more than 26 times in FA patients (range 22.00-82.00% with a mean of 48.32%) when compared to non FA patients (range 0.00-12.00% with a mean of 1.84%). The number of DEB-induced breaks/cells was more than 68 times higher in FA patients (range 0.26-4.39 with a mean of 1.37 breaks/cell) when compared to non FA patients (range 0.00-0.20 with a mean of 0.02 breaks/cell). The spontaneous chromosome fragility values in FA patients were overlapping those in non FA patients. Our results indicate that the DEB sensitivity test is the most reliable in vitro method for verification of the FA cellular phenotype.

Molecular analysis of ring y chromosome in a 10-year-old boy with mixed gonadal dysgenesis and growth hormone deficiency.

Ring Y chromosome is a very rare chromosomal aberration. The published mixed gonadal dysgenesis (MGD) patients with a ring Y chromosome are short in stature, but are not growth hormone (GH) deficient. We present the molecular cytogenetic and molecular characterization of ring Y chromosome mosaicism in a 10-year-old boy with MGD whose short stature could be explained by the high percentage of cells monosomic for the X-chromosome, but also by the presence of severe GH deficiency. The ring Y chromosome in our patient is a de novo structural aberration. The father's karyotype was normal.

Unbalanced 18q/21q translocation in a patient previously reported as monosomy 21.

We describe a patient in whom full monosomy 21 was initially assumed from routine GTG-banded karyotyping. Re-examination with chromosome painting demonstrated an unbalanced translocation between the long arms of chromosomes 18 and 21. Fluorescence in situ hybridisation (FISH) and microsatellite marker analysis revealed partial monosomy of chromosome 21 (pter-q21) and 18(q22-qter). The patient, 18 years old at the second examination, revealed multiple dysmorphic features, genital hypoplasia, dilated cerebral ventricles, muscular hypotonia and severe mental retardation. In not one out of all patients investigated postnatally in whom an initial examination had revealed monosomy 21, this could be confirmed by FISH; in all of them, re-examination detected an unbalanced rearrangement leading to only partial monosomy 21 plus partial monosomy of another chromosome to which the distal 21q segment was attached. Thus, it is still highly likely that full monosomy 21 is incompatible with intra-uterine survival.

Tetraploidy in a 26-month-old girl (cytogenetic and molecular studies).

Liveborn infants with tetraploidy are very rare in human pregnancies and usually die during the first days or months. Seven cases of liveborn infants with tetraploidy have previously been reported. Among them only two 92, XXXX infants survived for longer than 12 months. Here we report on the case of a 26-month-old girl with tetraploidy. The main clinical features of tetraploidy are facial dysmorphism, severely delayed growth and developmental delay. On the basis of molecular studies we discuss the possible origin of the additional chromosome sets in our proband. To our knowledge, this infant is the first reported case of tetraploidy who lived up to 26 months.

[Causes of ambiguous external genitalia in neonates]. / Uzroci dvopolnog izgleda spoljasnjih genitalija kod novoredjencadi.

INTRODUCTION: The classification of disorders such as ambiguous genitalia in newborns is difficult because similar or identical phenotypes could have several different aetiologies. In most cases it was impossible to correlate the aetiology of the disorder and the appearance of the external genitalia [1-3]. A newborn with ambiguous genitalia needs prompt evaluation that will permit gender assignment and detection of life-threatening conditions (salt-losing crisis due to congenital adrenal hyperplasia or Wilms' tumour). We studied the causes and characteristics of ambiguous genitalia in newborn infants over the period from 1990 to 1999. PATIENTS AND METHODS: The following genital phenotypes are considered as ambiguous: 1. Hypospadias with no palpable gonads; 2. Hypospadias with micropenis and no palpable gonads or one palpable gonad; 3. Newborn with female external genitalia and a gonadal mass in labia or labial fusion and/or clitoral enlargement [1, 4]. The diagnostic evaluation of newborns with ambiguous genitalia consisted of history and physical examination, determination of serum electrolytes, plasma 17-hydroxyprogesterone (17-OHP), chromosome analysis on cultured lymphocytes, sonogram of the abdomen in connection with a genitogram; and whenever it was necessary, basal plasma concentrations of testosterone and, after the stimulation with human chorionic gonadotropin (hCG), laparotomy for definitive determination of gonadal histology. All disorders with ambiguous genitalia have been classified in four groups: [6]: 1. Female pseudohermaphroditism (FPH); 2. Male pseudoherma phroditism (MPH); 3. True hermaphroditism (TH); 4. Asymmetrical gonadal dysgenesis (ASGD). RESULTS: The causes of sexual differentiation disorders in a group of 38 newborns with ambiguous genitalia are presented in Table 1. Main criteria for the diagnosis of FPH were normal female karyotype 46, XX, masculinization of external genitalia and no palpable gonads. Genitography revealed urogenital sinus and vagina, and ultrasound examination the uterus. During initial examination seven of 15 newborns with congenital adrenal hyperplasia (CAH) (Table 2) due to 21-hydroxylase (P450c21) deficiency (21-OHD) had clinical or laboratory signs of adrenal crisis. Two children had a simple virilizing form of 21-OHD. The female gender was chosen for these children. In other three patients with FPH isolated clitoral hyperplasia or labial fusion was the main reason for the studies. The common characteristics of newborns with MPH were as follows: normal male karyotype 46,XY with normally developed or dysgenetic testes, and/or good response to hCG stimulation. The complete androgen insensitivity (testicular feminization) was detected in two children (Table 3) with female external genitalia and palpable gonads in the labial folds, and female gender was chosen. The Denys-Drash syndrome was detected in one newborn with ambiguous genitalia, no palpable gonads, and normal response to hCG, and ultrasound findings of multiple bilateral renal tumours were identified as Wilms' tumour. In other newborns with MPH incomplete masculinization consisted of hypospadias, mostly of perineoscrotal type and of micropenis (penile size less than 2 cm) and/or bilateral or unilateral cryptorchidism (Table 3). In all children male sex was chosen. Asymmetrical gonadal dysgenesis was detected in two newborn infants. Both children had 46,XY/46,XX karyotype, testes on one side of the abdomen, and streak gonad on the other, developed vagina, uterus and unilateral Fallopian tube, and were raised as females. True hermaphroditism was established in one newborn with 46,XX karyotype, with a testis on one side of the abdomen and an ovotestis on the other side. The parents decided for male gender. The aetiology of ambiguous genitalia was not established in five children; in two children with 46,XY and one with 46,XX karyotype (with palpable gonads) the diagnostic study was not completed. CONCLUSIONS: The most common cause of ambiguous genitalia in our newborn patients was CAH due to 21-OH deficiency [2, 4, 6, 7]; 87 percent of patients had salt wasting form of the disease. In the majority of patients the appearance of the external genitalia made possible the detection of the disease immediately after the birth. So, the relative high incidence of adrenal crisis in our patients with CAH (38%) seems unreasonable. The decision for gender assignment was possible after the appropriate study of the nature of the disorder. The causes of MPH are numerous and heterogeneous [1, 3, 8]. With the exception of two patients with complete form of androgen insensitivity, in all newborns with MPH the male gender predominated. The appearance of external genitalia with severe perineoscrotal hypospadia and/or micropenis suggested the possibility of incomplete androgen resistance. If a male assignment is being considered, the response of the phallic size to treatment with testosterone was recommended. If penile size did not reach the 2.5 cm range or above, a male sex assignment was not advisable [1]. It is important for the paediatric surgeon to be involved in the diagnostic evaluation of these infants to plan the timing and techniques of the surgical reconstruction [6]. The decision to raise a patient with sex chromosome mosaicism, true hermaphroditism, or mixed gonadal dysgenesis as either a male or a female was based on the appearance of the external genitalia and possible fertility [1, 9]. The parental decision of male sex in our patients with true hermaphroditism could not be considered as optimal.

[Deletions in the dystrophin gene and its phenotype expression]. / Delecije u genu za distrofin i njihova fenotipska ekspresija.

About 60% of both Duchenne's muscular dystrophy (DMD) and Becker's muscular dystrophy (BMD) is due to deletions of dystrophin gene. For cases with deletion mutations the "reading frame" hypothesis predicts that deletions which result in disruption of the translation reading frame prevent production of stable protein and are associated with DMD. In contrast, intragenic deletions that involve exons encoding an integral number of triplet codons maintain proper reading frame. The resulting abnormal proteins are stable and partially functional, resulting in a milder and more variable BMD phenotype. To test the validity of this theory,we analyzed 40 patients-19 independent deletions at the DMD/BMD locus. Clinical/molecular correlations based on the altera-tions of the reading frame were valid in 69.2% of cases. After exclusion of: --2 patients with del 3-6 (with no consistent clinical expression); --1 DMD patient with large in-frame deletion; --2 patients that were too young to be classified; --4 patients in whom it was impossible to identify the extent of deletion (del 47 and del 44-45), the correlation between deletion and clinical severity was as predicted in 92.4% of cases. The present data should be useful in establishing the prognosis in individual patients even in sporadic cases with no affected relatives.

[Primary myelodysplastic syndrome in children]. / Sindrom primarne mijelodisplazije kod dece.

Primary MDS is a group of heterogenous clonal haematopoetic disorders. In a third of patients MDS terminates as acute myeloid leukaemia, usually resisitant to treatment, while the others succumb due to infections and haemorrhage. Conservative managements of MDS (chemotherapy, haematopoetic growth factors, modulation of cytokine network) are unsuccessful, while the bone marrow transplantation is the only definite treatment. We reviewed clinical and haematological presentations, frequency of dysplastic features, histological and cytogenetic findings in 29 children with primary MDS. Indications for haematological evaluation in our patients were symptoms and signs of isolated or combined cytopenias, fever of unknown origin and frequent infections. Hepatosplenomegaly was found in 19 (65%) patients, while this pattern was found in 10% of adult patients. Normochromic anaemia was found in 25 (86%) patients and thrombocytopenia in 23 (76%). Patients presenting pancytopenia had the lowest probability of survival. Degree of dysplasia, histology and kariotype of bone marrow had no influence on survival rates. Prognostic factors in paediatric MDS are of limited significance, as MDS in children is an absolute indication for bone marrow transplantation.

[Relation between gene mutations and pancreatic exocrine function in patients with cystic fibrosis]. / Povezanost izmedju genskih mutacija i egzokrine funkcije pankreasa kod osoba obolelih od cisticne fibroze.

Cystic fibrosis (CF), is the most common autosomal-recessive disease in Caucasians, with an incidence of approximately 1:2500 live births and a carrier frequency of approximately 4-5%. Causes of the disease are mutations in the CF gene which is located on chromosome 7 (region 7q31). Although a single mutation, a deletion of phenylalanine at position 508 (DF508) in exon 10, accounts for almost 70% of all CF chromosomes, over 900 other mutations have been identified in this large gene. CF gene encodes a membrane protein, which functions as aion channel- CFTR (cystic fibrosis transmembrane regulator protein). The exocrine pancreas is a gland that secretes water, enzymes and electrolytes into the intestinal lumen. These enzymes are needed for the normal digestion of food, and their reduced secretion in cystic fibrosis will cause malabsortion and malnutrition in CF patients. Pancreatic dysfunction in CF begins in uteri. Most patients with CF typically present insufficient pancreatic exocrine function (PI phenotype) and 10-15% of CF patients are pancreatic sufficient (PS phenotype). It has been shown elsewhere that the pancreatic function status in CF could be correlated to mutations in the CFTR gene. To determine the relation between genotype and pancreatic status, we analyzed 32 CF patients in whom both CF gene mutant alleles were identified (Table 1). Patients included in this study attended the Paediatric Department of Mother and Child Health Institute in Belgrade. The diagnosis was based on typical clinical manifestations and high levels of sweat chloride concentration (higher than 60 mmol/L). Of the 32 patients studied, only one (3.12%) was PS and the rest (96.88%) had PI phenotype. For each CF genotype the number of patients who were PI or PS is given in Table 1. The most striking observation was that all given genotypes correlated with either PI or PS, but not with both. On the basis of both preceding hypotheses and our present data (Table 2 and Table 3), it was possible to classify mutations as "severe" or "mild" with respect to pancreatic function (Table 4). This study strengthens the hypothesis that pancreatic function status in CF is genetically determined by specific mutations at the CF locus. Our data also strongly support the hypothesis that, with respect to pancreatic function, "mild" mutant alleles confer a higher residual CFTR activity than do "severe" mutant alleles. Although PS occurs in patients who have one or two "mild" mutations, PI occurs in patients who are homozygous or who are genetic compounds of two "severe" mutant alleles.

[The Angelman's syndrome]. / Angelmanov sindrom.

Distinction of patients with Angelman's syndrome in a group of mentally retarded patients is important even though the syndrome was rarely reported since the original description in 1965. Before that time these patients were thought to suffer from neurologic sequelae of perinatal asphyxia, Lennox-Gastaut syndrome or mental retardation of unknown origin. Diagnosis is based on the following criteria: developmental delay from early age, absent speech (or speech limited to less than six words), jerky movements with an ataxic gait if the patient is walking, paroxysm of inappropriate laughing, dysmorphic craniofacial features (brachycephaly, mid-facial hypoplasia, deep set eyes, macrostomia, prominent mandible). About 60% of patients have deletion of chromozome 15q11-13. Cytogenetic studies suggest that de novo deletion of chromozome 15 is connected with the low recurrence risk and that families with several members with Angelman's syndrome belong to the group without identifiable deletion on citogenetic or molecular level. The article deals with the diagnostic criteria, clinical features and electroencephalographic changes (after several years of followup) in seven children with Angelman's syndrome (four girls and three boys).

A case of monosomy 21.

A new case of monosomy 21 was observed in a newborn male. Characteristic clinical features include: an antimongoloid eye slants, large and low set ears, flat nose bridge, hypoplastic nipples, cardiac anomalies, muscular hypotonia, retarded psychomotor development. The karyotypes of the parents were normal.