Interstitial deletion in the long arms of chromosome 1: 46,XY,del(1)(pter leads to q22::q25 leads to qter)

Prenatal diagnosis of a rare de novo 1q22-q25.1 chromosomal deletion syndrome using oligo array CGH

We present prenatal diagnosis of a case with a rare de novo interstitial deletion of 1q21-q25.1 by oligo array CGH and provide detailed information on unbalanced gene content and the breakpoints. The affected fetus was delivered at 37 weeks' gestation with a unique clinical phenotype.

Refinement of genotype-phenotype correlation in 18 patients carrying a 1q24q25 deletion

Interstitial deletion 1q24q25 is a rare rearrangement associated with intellectual disability, growth retardation, abnormal extremities and facial dysmorphism. In this study, we describe the largest series reported to date, including 18 patients (4M/14F) aged from 2 days to 67 years and comprising two familial cases. The patients presented with a characteristic phenotype including mild to moderate intellectual disability (100%), intrauterine (92%) and postnatal (94%) growth retardation, microcephaly (77%), short hands and feet (83%), brachydactyly (70%), fifth finger clinodactyly (78%) and facial dysmorphism with a bulbous nose (72%), abnormal ears (67%) and micrognathia (56%). Other findings were abnormal palate (50%), single transverse palmar crease (53%), renal (38%), cardiac (38%), and genital (23%) malformations. The deletions were characterized by chromosome microarray. They were of different sizes (490 kb to 20.95 Mb) localized within chromosome bands 1q23.3-q31.2 (chr1:160797550-192912120, hg19). The 490 kb deletion is the smallest deletion reported to date associated with this phenotype. We delineated three regions that may contribute to the phenotype: a proximal one (chr1:164,501,003-167,022,133), associated with cardiac and renal anomalies, a distal one (chr1:178,514,910-181,269,712) and an intermediate 490 kb region (chr1:171970575-172460683, hg19), deleted in the most of the patients, and containing DNM3, MIR3120 and MIR214 that may play an important role in the phenotype. However, this genetic region seems complex with multiple regions giving rise to the same phenotype.

Maternal intrachromosomal insertional translocation leads to recurrent 1q21.3q23.3 deletion in two siblings

We identified a novel 6.33 Mb deletion of 1q21.3q23.3 (hg18; chr1: 153035245-159367106) in two siblings presenting with blepharophimosis, ptosis, microbrachycephaly, severe psychomotor, and intellectual disability. Additional common features include small corpus callosum, normal birth length and head circumference, postnatal growth restriction, low anterior hairline, upturned nose, bilateral preauricular pits, widely spaced teeth, gingival hypertrophy, left ventricular dilatation with decreased biventricular systolic function, delayed bone age, 5th finger clinodactyly, short 3rd digit, hyperconvex nails, obstructive and central sleep apnea, and bilateral heel contractures. Fluorescence in situ hybridization (FISH) performed in the mother of both children showed an apparently balanced, intrachromosomal insertional translocation of 1q21.3q23.3 to 1q42.12. The sibling recurrence likely arose by a maternal meiotic crossing over on the rearranged chromosome 1 between the deleted region and the insertion. We hypothesize that the decreased cardiac function and contractures may be related to LMNA haploinsufficiency. This case illustrates the importance of FISH when attempting to determine inheritance of a copy-number variation and emphasize the value of evaluating known haploinsufficiency phenotypes for genes in deleted regions.

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.

Distinctive phenotype in 9 patients with deletion of chromosome 1q24-q25

Reports of individuals with deletions of 1q24→q25 share common features of prenatal onset growth deficiency, microcephaly, small hands and feet, dysmorphic face and severe cognitive deficits. We report nine individuals with 1q24q25 deletions, who show distinctive features of a clinically recognizable 1q24q25 microdeletion syndrome: prenatal-onset microcephaly and proportionate growth deficiency, severe cognitive disability, small hands and feet with distinctive brachydactyly, single transverse palmar flexion creases, fifth finger clinodactyly and distinctive facial features: upper eyelid fullness, small ears, short nose with bulbous nasal tip, tented upper lip, and micrognathia. Radiographs demonstrate disharmonic osseous maturation with markedly delayed bone age. Occasional features include cleft lip and/or palate, cryptorchidism, brain and spinal cord defects, and seizures. Using oligonucleotide-based array comparative genomic hybridization, we defined the critical deletion region as 1.9 Mb at 1q24.3q25.1 (chr1: 170,135,865-172,099,327, hg18 coordinates), containing 13 genes and including CENPL, which encodes centromeric protein L, a protein essential for proper kinetochore function and mitotic progression. The growth deficiency in this syndrome is similar to what is seen in other types of primordial short stature with microcephaly, such as Majewski osteodysplastic primordial dwarfism, type II (MOPD2) and Seckel syndrome, which result from loss-of-function mutations in genes coding for centrosomal proteins. DNM3 is also in the deleted region and expressed in the brain, where it participates in the Shank-Homer complex and increases synaptic strength. Therefore, DNM3 is a candidate for the cognitive disability, and CENPL is a candidate for growth deficiency in this 1q24q25 microdeletion syndrome.

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.

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.

Proximal deletion of the long arm of chromosome 1: [del(1)(q23-q25)]

A patient with bilateral complete cleft of the lip and palate (CLP) had a proximal deletion of the long arm of chromosome 1 (1q). This rare chromosomal abnormality was characterized by pre- and postnatal growth retardation, psychomotor retardation, and specific craniofacial and other systemic anomalies. There is a high incidence of CLP in proximal 1q deletion syndrome, especially bilateral CLP. Twelve other cases reported in the literature having this deletion and associated anomalies were reviewed.

Molecular characterization of a patient with del(1)(q23-q25)

We report a patient (S.T.) with multiple congenital anomalies and developmental delay associated with an interstitial deletion of 1q23-1q25. Molecular analysis of the deletion was performed using DNA markers that map to 1q. Five DNA markers, MLAJ-1 (D1S61), CRI-L1054 (D1S42), HBI40 (D1S66), OS-6 (D1S75), and BH516 (D1S110), were demonstrated to be deleted. Informative polymorphisms demonstrated this to be a de novo deletion of the maternally derived chromosome. Deletion status was determined using restriction fragment length polymorphism (RFLP) analysis supplemented with densitometry in the experiments where RFLP analysis was not fully informative. Deletions were confirmed by Southern analysis using genomic DNA from a somatic cell hybrid retaining the del(1)(q23-q25) chromosome that was constructed from patient S.T. Flow karyotyping confirmed the deletion and estimated that the deletion encompassed 11,000-16,000 kb. The clinical and cytogenetic characteristics of S.T. are compared with those of ten previously described patients with monosomy 1q21-1q25.

Lip pits and deletion 1q32----41

A patient with an interstitial deletion of chromosome 1q[del(1q32----41)] was found to have, among other anomalies, congenital lower-lip pits. Lip pits are rare and are found mainly in association with the van der Woude syndrome and the popliteal pterygium syndrome; we cannot find a report of their association with a chromosome anomaly. To our knowledge, interstitial deletion of the segment 1q32----41 has not been reported. This observation raises the possibility that the van der Woude syndrome may be due to a submicroscopic deletion of chromosome 1q.

Two cases of interstitial deletion of the long arm of chromosome 1: del(1)(q21----q25) and del(1)(q41----q43)

Two unrelated children, one with a proximal interstitial deletion 1 (1(pter----q21: :q25----qter] and the other one with a distal interstitial deletion 1 (1(pter----q41: :q43----qter] are presented. The clinical features of the patient with a proximal deletion (q21-q25) correspond with those of eight earlier reported cases with a deletion 1q21/22/23----q25. The second patient with the distal interstitial deletion (q41-q43) is the first case published as far as we know. The clinical characteristics of the latter patient are compared with those of six cases with a terminal deletion 1q with at least one common band missing (1q42).