Confirmation and refinement of the genetic localization of the Coffin-Lowry syndrome locus in Xp22.1-p22.2

The Coffin-Lowry syndrome (CLS) is an X-linked inherited disease of unknown pathogenesis characterized by severe mental retardation, typical facial and digital anomalies, and progressive skeletal deformations. Our previous linkage analysis, based on four pedigrees with the disease, suggested a localization for the CLS locus in Xp22.1-p22.2, with the most likely position between the marker loci DXS41 and DXS43. We have now extended the study to 16 families by using seven RFLP marker loci spanning the Xp22.1-p22.2 region. Linkage has been established with five markers from this part of the X chromosome: DXS274 (lod score [Z] (theta) = 3.53 at theta = .08), DXS43 (Z(theta) = 3.16 at theta = .08), DXS197 (Z(theta) = 3.03 at theta = .05), DXS41 (Z(theta) = 2.89 at theta = .08), and DXS207 (Z(theta) = 2.73 at theta = .13). A multipoint linkage analysis further placed, with a maximum multipoint Z of 7.30, the mutation-causing CLS within a 7-cM interval defined by the cluster of tightly linked markers (DXS207-DXS43-DXS197) on the distal side and by DXS274 on the proximal side. Thus, these further linkage data confirm and refine the map location for the gene responsible for CLS in Xp22.1-p22.2. As no linkage heterogeneity was detected, this validates the use of the Xp22.1-p22.2 markers for carrier detection and prenatal diagnosis in CLS families.

[Dubowitz syndrome. A diagnosis not to be missed]

Dubowitz syndrome is a rare hereditary disorder whose main features are intra-uterine and post-natal growth retardation, characteristic facies, microcephaly, mental retardation and poor feeding. Because of the eczema which was present in half of the cases after 4 years of age, it cannot be mistaken for the more frequent fetal alcohol syndrome. We report 5 cases, among whom two sibs, confirming the recessive autosomal mode of inheritance and the necessity for genetic counseling.

Statistical approaches for the detection of heterozygotes for biotinidase deficiency

We applied and evaluated 3 statistical approaches for the detection of heterozygotes for biotinidase deficiency in a randomly selected population of French adults. The first method, which used a cutoff value to dichotomize the population, lacked sensitivity. The second approach calculated the probability of heterozygosity for a given enzyme activity through the application of Bayes theorem to the normal density functions of the enzyme distributions of the obligate heterozygote and the test populations. A priori values of the means and standard deviations (SDs) of the genotypic distributions were used. This method was sufficiently sensitive for both population screening and genetic counseling, but requires prior knowledge of the frequency of the deficient gene (q). The third approach was similar to the second, however, maximum likelihood estimates of the means and SDs of the genotypic distributions were calculated and used to determine the probability of heterozygosity for a given enzyme activity. This method was as sensitive as the second method and is appropriate for screening populations for which there is little prior information about the gene frequency and the genotypic distributions. This method can also be used to estimate the gene frequency of the disorder within a given ethnic or racial population. Using this method, we estimated the frequency of heterozygotes (2pq) in the French population to be 0.012, which was similar to that estimated from the results of neonatal screening for biotinidase deficiency. These methods can be used to detect heterozygotes and to estimate the gene frequency of other inherited enzyme deficiencies.

[Apert's syndrome with polymetatarsia]

Three cases of acrocephalosyndactyly with duplication of the first toe and presence of six well-individualized metatarsals are reported. This type of polysyndactyly should suggest the diagnosis of Carpenter syndrome, which is inherited on a recessive autosomal basis. However, in the three patients reported here, the facial dysmorphism was distinct from that seen in Carpenter syndrome and the syndactyly was more marked. The correct diagnosis therefore seems to be Apert acrocephalosyndactyly, a disease with dominant transmission. A mutation seems very likely and consequently the risk of recurrence in siblings is probably minimal.

[Waardenburg's syndrome and severe cyanotic cardiopathy]

Waardenburg syndrome type I is transmitted as an autosomal dominant trait. The main features are dystopia canthorum, partial pigmentary disorder and perceptive deafness. Osteo-articular and intestinal malformations may be observed. In an affected family, the unusual combination of Waardenburg syndrome and severe congenital heart disease has been observed in a child.

[Embryonal rhabdomyosarcoma diagnosed antenatally]

A case of congenital embryonal rhabdomyosarcoma of the right shoulder is described. The patient was the first child born to a 24 year-old woman who had previously been treated for sterility. The diagnosis was made by echography during the 36th week of gestation. This full term white boy was born by cesarean section because of the tumor size. Surgical treatment was completed by chemotherapy. Despite 4 courses of VAC, local recurrence was noted that led to a second surgical excision followed by a new cyclic chemotherapy (IVA). The treatment was fairly well tolerated. The child is well 24 months later.

[An example of detection of heterozygotes and antenatal diagnosis in four families with anhidrotic ectodermal dysplasia]

Anhidrotic ectodermal dysplasia is an X-linked inherited skin disorder; only affected males exhibit the complete syndrome, whereas females may have a few mild features. The gene involved in this disease is located in the proximal area of the long arm of the X chromosome, in the q13 position. Molecular analysis is very helpful for calculating the risk of transmission in sisters with normal phenotypes and affected individuals (family 1 provides an example), but cannot solve all problems (example of family 4). The best results are obtained when there are two informative markers, each located on either side of and very close to the mutant gene. Molecular analysis can also be applied to chorionic villi sampled at the tenth week of gestation in order to achieve antenatal diagnosis in male fetuses in high risk families. Until recently, antenatal diagnosis could be performed only at the twentieth week of gestation by the demonstration of inadequate development of skin glands in skin biopsy specimens sampled under fetoscopy. Family 2 provides an example of antenatal diagnosis and highlights the risk of error that always exists in molecular analysis studies.

[Diverticulum of the stomach in children. Apropos of a case of congenital diverticulum]

We describe a patient with a large diverticulum of the gastric fundus disclosed by an episode of epigastric pain. Hematemesis occurred, requiring surgical removal of the diverticulum. Gastric diverticula are uncommon embryologic anomalies that are usually asymptomatic. Surgical treatment is necessary if a complication develops.

[Respiratory arrest in an asthmatic girl treated with beta-2-mimetics and theophylline. Possible role of hypokalemia in sudden death in asthmatic patients]

We report a case of respiratory arrest in a ten-year-old asthmatic girl under beta-2-agonists and theophylline. The possibility that hypokalemia plays a part in the sudden deaths seen in some asthmatic patients is discussed.

[Tumor epilepsy. Apropos of a case of temporal astrocytoma]

We report the case of a 15-year-old who sustained neonatal distress and subsequently presented temporal seizures. These were ascribed only several years later to a temporal astrocytoma. Tumor-related epilepsy is infrequent in children. Tumors may be responsible for a pattern of isolated partial epilepsy of several years duration. Advances in medical imaging techniques ensure earlier diagnosis, but some CT scan images may be difficult to read. CT scan is not indicated in functional epilepsy but should be performed in partial epilepsy with no known etiology.

[The importance of continuous ambulatory peritoneal dialysis technics in relation to intermittent peritoneal dialysis in acute renal insufficiency in children. Apropos of 7 cases]

We report seven cases of acute renal failure (ARF) treated by continuous ambulatory peritoneal dialysis (CAPD). ARF was caused by hemolytic uremic syndrome in six patients and acute fetal distress in one neonate. Mean age was 28 months (range 6 days-6 years). A flexible Tenckhoff catheter was inserted surgically under brief (10 minutes) general anesthesia in all patients. During the first 24 hours, in order to avoid clogging of the catheter, exchanges were done every 45 minutes with 20 ml/kg dialysate initially, gradually increased to 40-50 ml/kg. Thereafter, 5 to 8 exchanges were done every day (mean duration 9 days, range 4-21) until creatinine clearance reached 15 ml/mn/1.73 m2. No case of peritonitis or leakage was recorded. In two patients, migration of the straight catheter caused flow obstruction. None of the crook-shaped catheters migrated. Because dialysis was continuous and fluid balance could be controlled by using a hypertonic dialysate if called for, optimal protein (1-1.5 g/kg/d) and energy intake were possible. This intake was ensured mainly by continuous enteral nutrition. Improved patient comfort (no immobilization, no repeated punctures) and staff comfort (technical simplicity, independence from a cycler) are further non-negligeable advantages of CAPD.

[Erythroblastopenia caused by parvovirus in siblings, revealing a hereditary spherocytosis. Apropos of a case]

Following the occurrence in two siblings of parvovirus B19-related acute transient erythroblastopenia with specific IgMs, hereditary spherocytosis (HS) was diagnosed for the first time in the two patients as well as in three other members of the family.

[African trypanosomiasis in children treated with eflornithine. A case]

We report the case of a 14-year old African girl presenting with late-stage African T. gambiense trypanosomiasis. She was treated with eflornithine, an ornithine decarboxylase inhibitor which is a key enzyme in the biosynthesis of polyamine. Polyamines are essential to the multiplication of trypanosomes. Two treatment courses were necessary to achieve an apparent cure after one year; however, a longer follow up will be required to confirm whether or not the cure is permanent. Determination of drug concentrations in plasma and cerebrospinal fluid was performed during the second treatment course. Side-effects were easily controlled.

[Role of ultrasound in studying the first urinary infection in children]

A retrospective study comparing the findings of ultrasonography (5 MHz transducer) versus intravenous pyelography and voiding cystourethrography was conducted in 92 patients during the course of an initial urinary tract infection (greater than or equal to 10(5) bacteriae/ml, WBC greater than 25/mm3) gathered over a period of 5 years. The average interval of time between ultrasonography and intravenous pyelography was 8 days (range 1-70). False positive results for ultrasonography were noted in 11% (5 of 45 cases), while false negatives were observed in 36% (17 of 47). Of the 47 cases of obstructive uropathy diagnosed by conventional means, ultrasonography missed the diagnosis in 1 case of ureteral duplication as well as in 16 children with vesicoureteral reflux. In comparison, intravenous pyelography missed 8 of these 21 cases of vesicoureteral reflux. Overall sensitivity of ultrasonography was mediocre at 64% but excellent at 96% after excluding cases with vesicoureteral reflux. Specificity was poor for the group of patients with vesicoureteral reflux (33%) and did not improve when they were excluded (40%). Sensitivity and specificity were comparable whatever the age group. In conclusion, we would recommend that when both ultrasonography and voiding cystourethrography are normal in children with a urinary tract infection, intravenous pyelography could safely be deferred.

[Teratogenic risk during treatment of Wilson disease]

Untreated Wilson's disease usually causes infertility or abortion, as a result of increased intrauterine copper level. Therefore, a chelation treatment is necessary during the whole pregnancy. The most used is D-Penicillamine whose teratogenic risks such as cutis laxa, dermatopathy or complex mesenchyme abnormalities are paradoxically rare in the new borns of treated Wilson's disease mothers, perhaps owing to hypercupremia that protects the foetus from excessive copper deficiency. Yet, it's wise to reduce chelation treatment about a quarter fold and to add 50 mg vitamin B6 weekly as we did in our case whose child was born normal.

Evaluation of D-penicillamine in juvenile chronic arthritis. A double-blind, multicenter study

Seventy-four children with juvenile chronic arthritis were entered into a 6-month, multicenter, comparative double-blind study of the efficacy of D-penicillamine versus placebo. The results were evaluated in 70 patients, 55 of whom completed 6 months of the study. Improvement was observed in the total number of stiff joints, total number of painful joints, and total severity index measuring joint pain. There was also a significant reduction in the concurrent use of nonsteroidal anti-inflammatory drugs. D-penicillamine was well-tolerated in all but 2 patients. Some children in the placebo group exhibited definite improvement; however, relapses that were observed were mainly in that group. These results confirm the efficacy of D-penicillamine for the treatment of joint involvement in juvenile chronic arthritis.