Multiple congenital anomalies/mental retardation (MCA/MR) syndrome due to interstitial deletion 1q

Infantile hypertrophic pyloric stenosis--genetics and syndromes

Infantile hypertrophic pyloric stenosis (IHPS) is a common condition in neonates that is characterized by an acquired narrowing of the pylorus. The aetiology of isolated IHPS is still largely unknown. Classic genetic studies have demonstrated an increased risk in families of affected infants. Several genetic studies in groups of individuals with isolated IHPS have identified chromosomal regions linked to the condition; however, these associations could usually not be confirmed in subsequent cohorts, suggesting considerable genetic heterogeneity. IHPS is associated with many clinical syndromes that have known causative mutations. Patients with syndromes associated with IHPS can be considered as having an extreme phenotype of IHPS and studying these patients will be instrumental in finding causes of isolated IHPS. Possible pathways in syndromic IHPS include: (neuro)muscular disorders; connective tissue disorders; metabolic disorders; intracellular signalling pathway disturbances; intercellular communication disturbances; ciliopathies; DNA-repair disturbances; transcription regulation disorders; MAPK-pathway disturbances; lymphatic abnormalities; and environmental factors. Future research should focus on linkage analysis and next-generation molecular techniques in well-defined families with multiple affected members. Studies will have an increased chance of success if detailed phenotyping is applied and if knowledge about the various possible causative pathways is used in evaluating results.

De novo deletion of 1q31.1-q32.1 in a patient with developmental delay and behavioral disorders

We describe the case of a 6-year-old boy with a de novo deletion of the long arm of chromosome 1 encompassing band 1q31.1-q32.1, minor facial anomalies, mild developmental delay, and behavioral disorders. His postnatal karyotype was normal. Using array-comparative genomic hybridization, we identified and characterized a de novo 1q interstitial deletion of about 15.6 Mb, which partially overlaps those of other reported cases. We considered the gene content of the deleted region in an attempt to compare the clinical features of our patient with these other cases, even though they were not characterized molecularly in detail. The most remarkable difference was the absence of microcephaly. To the best of our knowledge, this is the first report of a de novo 1q31.1-q32.1 deletion. Moreover, it illustrates how molecular delineation associated with fine clinical characterization can improve the genotype-phenotype correlations of classical cytogenetic abnormalities.

Salt-wasting 21-hydroxylase deficiency congenital adrenal hyperplasia and pyloric stenosis in two Hispanic brothers

The differential diagnosis of vomiting and dehydration in the first month of life includes congenital adrenal hyperplasia (CAH) and pyloric stenosis (PS). Each diagnosis may mask the presence of the other, requiring careful evaluation and follow-up. We document the occurrence of CAH and PS in two Hispanic siblings.

Prenatal diagnosis and molecular characterization of an interstitial 1q24.2q25.2 deletion

We report on the observation of an interstitial deletion of the long arm of chromosome 1 diagnosed prenatally in a 28 weeks gestation fetus by standard karyotype. Amniocentesis was performed because of an increased Down syndrome maternal serum screening and ultrasonographic abnormalities. Fetus autopsy showed an intrauterine growth retardation, dysmorphic features and limbs abnormalities. Using fluorescent in situ hybridization technique (FISH), we characterized the deletion boundaries corresponding to the bacterial artificial chromosomes (BAC) RP11-193J5 and RP11-162L13. Molecular studies identified the deletion of paternal origin. Therefore the karyotype was interpreted as 46,XY,del(1)(q24.2q25.2). This is the smallest deletion of the long arm of chromosome 1 reported prenatally and characterized at the molecular level. Its phenotype is compared to other similar cases described in the literature.

Interstitial 1q25.3-q31.3 deletion in a boy with mild manifestations

We describe a 4-year-old boy with an accessory right thumb, short and broad toes, cryptorchidism, micrognathia, abnormally modeled ears, and delayed speech development. The chromosome analysis of patient's peripheral blood lymphocytes by conventional GTG banding demonstrated a small deletion in the long arm of chromosome 1. Confirmation and defined localization of the deleted segment to chromosomal bands 1q25.3-q31.3 was obtained by high resolution prometaphase analysis. Molecular studies, using a set of polymorphic chromosome 1q specific microsatellite markers, localized the deletion between the markers D1S2127 and D1S1727 on the paternally inherited chromosome 1. The maximum physical distance between these markers is approximately 21 Mb. The previously described two patients with 1q25-q31 deletions both had severe clinical manifestations, just as the other 10 patients with the proposed "intermediate 1q deletion syndrome," associated with 1q25-q32 deletions. Distinct from all these patients, the clinical picture of our patient is markedly milder, i.e., without growth retardation, microcephaly, or clear mental retardation.

A patient defines the interstitial 1q deletion syndrome characterized by antithrombin III deficiency

A patient with microbrachycephaly, high forehead, long philtrum, thin upper lip, downturned corners of the mouth, low set ears with overlapping helix, fifth-finger clinodactyly, small hands and feet, bilateral transverse palmar crease, low total finger ridge count, hypotonia, severe growth and psychomotor delay, mild hypoplasia of corpus callosum, and Arnold-Chiari type 1 malformation is reported. The karyotype showed 46, XY, del(1)(q23q31.2). Coagulation factor V (F5, 1q23) and coagulation factor XIII (F13B, 1q31-q32.1) levels were normal. As expected, antithrombin III (AT3, 1q23-q25.1) serum level and activity were half of normal. We performed a review of the literature on proximal and intermediate deletion 1q syndrome, and we hypothesize the existence of only one 1q interstitial deletion syndrome, clinically characterized by ATIII deficiency.

Paracentric inversions in humans: a review of 446 paracentric inversions with presentation of 120 new cases

We present a large review of 446 cases of paracentric inversions (PAI), including 120 new cases, to assess their incidence, distribution, inheritance, modes of ascertainment, interchromosomal effects, viable recombinant offspring, and clinical relevance. All 23 autosomes and sex chromosomes had inversions. However, none were identified in chromosome arms 18p, 19q, 20q, and Yp. PAI were most commonly reported in chromosomes 1, 3, 5, 6, 7, 11, and 14 and less frequently in chromosomes 4, 16, 17, 18, 19, 20, 21, 22, and Y. Inversions were most common in chromosome arms 6p, 7q, 11q, and 14q and observed least in chromosome arms 2p, 2q, 3q, 4q, and 6q. Frequently encountered breakpoints included 3(p13p25), 6(p12p23), 6(p12p25), 7(q11q22), and 11(q21q23). Ascertainment was primarily incidental (54.5%), mental retardation and/or congenital anomalies (22.2%), spontaneous abortions (11.4%), associations with syndromes (3.0%), and infertility (2.0%) accounted for the remainder. Ascertainment was neither related to the length of the inverted segment nor to specific inversions except for PAI of Xq which often presented with manifestations of Ullrich-Turner syndrome. Sixty-six percent of PAI were inherited while 8.5% were de novo. Recombination was observed in 17 cases, 15 of which resulted in a monocentric chromosomal deletion or duplication. No common factors were identified that suggested a tendency towards recombination. The incidence of viable recombinants was estimated to be 3.8%. This review documents that PAI are perhaps more commonly identified than suggested in previous reviews. Despite the possible bias of ascertainment in some cases, there may be associated risks with PAI that require further examination. Our data suggest that PAI carriers do not appear to be free of risks of abnormalities or abnormal progeny and caution is recommended when counseling.

Multiple craniofacial anomalies associated with an interstitial deletion of chromosome 1(q21->q25)

We present a patient with an interstitial deletion of the chromosome 1q21->q25 that was diagnosed by amniocentesis. Significant malformations included: microbrachycephaly, bilateral cleft lip and palate, micrognathia, short neck, and athyroidia. The autopsy results demonstrate an overlap with several other postnatally ascertained patients and document the phenotype prenatally.

De novo reciprocal 1p;2q translocation in a child with multiple congenital anomalies/mental retardation syndrome

A newborn male infant was found to have an unusual pattern of congenital anomalies associated with an apparently balanced de novo reciprocal translocation: 46,XY,t(1;2)(p22;q22). The infant had a previously apparently undescribed multiple congenital anomalies and mental retardation syndrome.

Interstitial deletion of chromosome 1 [del(1)(q25q32)] in an infant with prune belly sequence

Relatively few cases of deletion 1q have been reported. These cases have been divided into three groups according to assigned breakpoints. They include proximal interstitial, intermediate interstitial, and terminal deletions. We present a male infant with an interstitial deletion of 1q with breakpoints determined by GTG banding as q25 and q32. Comparison with similar case reports suggests common physical features which include microcephaly, growth retardation, developmental delay, clinodactyly, and genital anomalies in affected males. However, no characteristic phenotypic appearance is definable. The infant also presented with prune belly sequence (PBS) with Potter facies. Fetal ascites, as noted in this case on prenatal ultrasound, appears to be an early factor in the pathogenesis of PBS. Therefore, detection of fetal ascites should suggest the presence of the PBS association and the need for more extensive prenatal evaluation.

Interstitial deletion of the long arm of chromosome 1 [del(1)(q32q42)]

A severely malformed girl died 7 days after birth and was found to have de novo interstitial deletion of 1q (1q32----1q42). Clinical abnormalities included microcephaly, encephalocele, small eyes with unilateral esotropia, hypertelorism but small prominent nose, highly arched palate, micrognathia, abnormal cry, apparently abnormal low-set ears, short neck with low posterior hair line, narrow shoulders, congenital heart defect, hypoplastic nails, overlap of toes with flat feet, and single umbilical artery.