Interstitial deletion 2(p11.2p13): a rare chromosomal abnormality

We report on an infant with a karyotype of 46,XY,del(2) (p11.2p13), the fourth reported case in the literature. At birth, the child had eventration of the diaphragm. His phenotype was suggestive of a connective tissue disorder with scoliosis, pectus carinatum, long slender fingers, camptodactyly, cryptorchidism, hypertonia and myopia. His facial appearance was mildly dysmorphic and strongly resembled a previously reported patient with the same deletion. The child expired at 2 months of age. Some generalizations can be made about the phenotype for del(2)(p11.2p13), despite reporting of cases at different ages.     

Rare interstitial deletion (2)(p11.2p13) in a child with pericentric inversion (2)(p11.2q13) of paternal origin.

An unbalanced 46,XY,der(2)del(2)(p11.2p13) inv(2)(p11.2q13) karyotype was found in a phenotypically abnormal child with a de novo interstitial deletion of band 2p12 associated with an inv(2)(p11.2q13) inherited from the father. The inv(2) is generally considered a benign familial variant without significant reproductive consequences. However, our findings led us to consider a previously proposed mechanism of unequal meiotic crossing over at the base of a parental inversion loop, which could lead to either a deletion or duplication of a segment adjacent to the inverted region in the offspring. This phenomenon has been reported in other inversions of chromosomes 1, 7, 13, 15, and 17 and may explain the origin of the deletion in our patient. Although repetitive sequences might be present around such inversions, which could predispose to de novo deletions independently of the inversion, current evidence including this case favors a proposed causal relationship between the parental inversion and the deletion in the child. Our review and results suggest there could be a small risk for a related imbalance to couples with an inv(2)(p11.2q13). For del(2)(p11.2p13), which is rare, a more distinct phenotype has been proposed herein. Our patient shared several findings with the three previously published cases, namely the broad nasal bridge, abnormal ears, high-arched palate, psychomotor retardation, and micrognathia. However, our patient also had sensorineural hearing loss and significant hypotonia, which have not been previously reported, thereby expanding our understanding of this rare deletion. Am. J. Med. Genet. 87:139-142, 1999. Published 1999 Wiley-Liss, Inc.     

Rare interstitial deletion (2)(p11.2p13) in a child with pericentric inversion (2)(p11.2q13) of paternal origin

An unbalanced 46,XY,der(2)del(2)(p11.2p13) inv(2)(p11.2q13) karyotype was found in a phenotypically abnormal child with a de novo interstitial deletion of band 2p12 associated with an inv(2)(p11.2q13) inherited from the father. The inv(2) is generally considered a benign familial variant without significant reproductive consequences. However, our findings led us to consider a previously proposed mechanism of unequal meiotic crossing over at the base of a parental inversion loop, which could lead to either a deletion or duplication of a segment adjacent to the inverted region in the offspring. This phenomenon has been reported in other inversions of chromosomes 1, 7, 13, 15, and 17 and may explain the origin of the deletion in our patient. Although repetitive sequences might be present around such inversions, which could predispose to de novo deletions independently of the inversion, current evidence including this case favors a proposed causal relationship between the parental inversion and the deletion in the child. Our review and results suggest there could be a small risk for a related imbalance to couples with an inv(2)(p11.2q13). For del(2)(p11.2p13), which is rare, a more distinct phenotype has been proposed herein. Our patient shared several findings with the three previously published cases, namely the broad nasal bridge, abnormal ears, high-arched palate, psychomotor retardation, and micrognathia. However, our patient also had sensorineural hearing loss and significant hypotonia, which have not been previously reported, thereby expanding our understanding of this rare deletion. Am. J. Med. Genet. 87:139–142, 1999. Published 1999 Wiley-Liss, Inc.     

De novo direct duplication 2 (p12 p21) with paternally inherited pericentric inversion 2p11.2 2q12.2

We report a 4-year-old girl with a previously undescribed de novo duplication of 2p12 → 2p21 on the same homologue as a paternally inherited pericentric inversion of region 2p11.2 → 2q12.2, resulting in dysmorphic features, cardiac abnormality, cleft palate, respiratory problems, severe growth retardation and developmental delay. This case raises an important question - did the paternal pericentric inversion influence the occurrence of the de novo duplication?     

De novo 16p deletion: ATR-16 syndrome

We describe a child with α-thalassemia ascertained by newborn screening. Evaluation at 9 months of age showed minor anomalies and developmental delay. Chromosomal analysis demonstrated a de novo deletion of the most distal portion of the short arm of chromosome 16, which contains the α-globin genes. Analysis of the α-globin locus by Southern blot analysis did not demonstrate altered band sizes at this locus; however, analysis of the films using densitometry confirmed hemizygosity. This is the fifth reported case of the ATR-16 syndrome (α-thalassemia retardation-16) not complicated by duplication or deletion of other chromosomes. Am. J. Med. Genet. 72:451–454, 1997. © 1997 Wiley-Liss, Inc.     

De novo partial duplication of 17p [dup(17)(p12----p11.2)]: clinical report

Duplication of band p11.2 and a small proximal portion of band p12 of chromosome 17 was noted in an infant with unusual facial appearance and left calcaneovalgus deformity. Developmental delay was documented over time. Only one other similar case has been found in the literature, but deletion of the same region is known in nine recently described cases [Smith et al, 1986]. This suggests that abnormalities of this small region of 17p are relatively common and only recently detectable with modern high-resolution techniques.     

Multi-disciplinary clinical study of Smith-Magenis syndrome (deletion 17p11.2)

Smith-Magenis syndrome (SMS) is a multiple congenital anomaly, mental retardation (MCA/MR) syndrome associated with deletion of chromosome 17 band p11.2. As part of a multi-disciplinary clinical, cytogenetic, and molecular approach to SMS, detailed clinical studies including radiographic, neurologic, developmental, ophthalmologic, otolaryngologic, and audiologic evaluations were performed on 27 SMS patients. Significant findings include otolaryngologic abnormalities in 94%, eye abnormalities in 85%, sleep abnormalities (especially reduced REM sleep) in 75%, hearing impairment in 68% (approximately 65% conductive and 35% sensorineural), scoliosis in 65%, brain abnormalities (predominantly ventriculomegaly) in 52%, cardiac abnormalities in at least 37%, renal anomalies (especially duplication of the collecting system) in 35%, low thyroxine levels in 29%, low immunoglobulin levels in 23%, and forearm abnormalities in 16%. The measured IQ ranged between 20–78, most patients falling in the moderate range of mental retardation at 40–54, although several patients scored in the mild or borderline range. The frequency of these many abnormalities in SMS suggests that patients should be evaluated thoroughly for associated complications both at the time of diagnosis and at least annually thereafter. © 1996 Wiley-Liss, Inc.     

De novo interstitial deletion del(1)(p21p32).

A girl aged 14 years 9 months, overweight, with severe psychomotor retardation, short stature, a sheep-like face, malformed ears, skeletal and dermatoglyphic abnormalities, and partial deletion of the short arm of chromosome 1 is presented. The karyotype was 46,XX,del(1)(qter to p22::p32 to pter).     

De novo trisomy 16p11.2-qter: report of an infant

We report on a four-month-old girl with a de novo trisomy 16q [47,XX, +del(16)(p11.2).ish del(16)(p11.2)(wcp16+,D16Z2+,tel16q+, tel16p-)]. She had minor facial anomalies, limb anomalies, urogenital abnormalities, and severe cardiovascular defects. Autopsy confirmed left hypoplastic lung, total anomalous pulmonary venous drainage via coronary sinus, persistent left superior vena cava, patent ductus arteriosus, secundum atrial septal defect, bilateral hydronephrosis and hydroureters, uterus bicornis, and ovarian hypoplasia. Short tandem repeat polymorphism analysis indicated that the additional, structurally abnormal chromosome 16 was maternal in origin.     

De novo interstitial deletion of 1p (pter----p34.1::p32.3----qter).

We report a case of a 9 month old girl with a de novo interstitial deletion of 1p, karyotype 46,XX, del(1)(pter----p34.1::p32.3----qter). She had dysmorphic features including upward slanting palpebral fissures, a bulbous nose, a long philtrum, low set and malformed ears, a short neck, hypoplastic nails on both index fingers, widened interdigital spaces between the toes, dilated lateral ventricles, right hydronephrosis, a dilated right ureter, mental and motor developmental delay, and generalised hypotonia.     

Interstitial deletion of (17)(p11.2p11.2) in nine patients

We describe a new and distinct syndrome involving an interstitial deletion of short arm of chromosome 17 in nine unrelated patients (six males; three females) ranging in age from 3 months to 65 years. In eight patients, a deletion of a portion of band 17p11.2 was associated with a striking similar phenotype including brachycephaly, midface hypoplasia, prognathism, hoarse voice, and speech delay with or without hearing loss, psychomotor and growth retardation, and behavior problems. The one patient with a complete deletion of band 17p11.2 was more severely affected with facial malformations, cleft palate, and major anomalies of cardiac, skeletal, and genitourinary systems; the patient died at age 6 months. Careful cytogenetic analysis including high-resolution techniques will be important for the further identification of patients with this previously unrecognized deletion syndrome.     

De novo 13q partial duplication identified by cytogenetic, biochemical and molecular approaches

A 3.5-month-old female infant manifesting dysmorphic facies, developmental delay and failure to thrive was referred for cytogenetic evaluation. Peripheral lymphocytes revealed three chromosomally distinct cell lines: 46,XX/46,XX,10p+/47,XX,10p+,+mar. Dermal fibroblasts revealed only the 46,XX,10p+cell line. High resolution G-, R-, and Q-banding suggested that the extra chromosomal material (10p+) represented a duplication of the segment 13q14----13qter. Parental karyotypes were normal. As absolute identification of de novo chromosomal abnormalities, based solely on cytogenetic studies, is sometimes difficult, both biochemical and molecular approaches were undertaken to elucidate this abnormality in more detail. Dosage effects were examined using esterase D (localized to 13q14.1) and the DNA probes p1E8 and p9A7 (localized to 13q22 and 13q31/32, respectively). These studies suggested the presence of only 2 copies of esterase D, but 3 copies of both DNA probes, allowing identification of the breakpoint at 13q14.2.     

De novo duplication of 17p [dup(17)(p12----p11.2)]: report of an additional case with confirmation of the cytogenetic, phenotypic, and developmental aspects.

We describe an apparent de novo duplication of bands 17p11.2 and p12. A comparison of the manifestations of a previously reported case with a similar karyotype [Magenis et al., Am J Med Genet 24:415-420 (1986)] and of our own case seems to indicate a characteristic pattern which includes prenatal and postnatal growth retardation, facial changes, club feet, and mild developmental deficits. The prominent facial changes are a relatively triangular face, downslanted palpebral fissures, malocclusion, and abnormal ears. In addition, this condition appears to be milder than other duplications of the short arm of chromosome 17, namely trisomy 17p and dup(17)(p11.2----cen).     

A case of de novo interstitial deletion of chromosome 9(p12p13)

The present paper describes a girl with a small de novo deletion of chromosome 9(p12p13). This deletion has not been published previously. The deleted fragment is clearly outside the region involved in the so-called deletion 9p syndrome. The patient had mild dysmorphic features and feeding problems during the first weeks of life, but is now developing well. Because of the lack of severe clinical features in this patient, we speculate that the deletion may be prevalent in other patients who have no clinical indication for chromosome investigation.     

De novo simultaneous reciprocal translocation and deletion.

A female infant with severe mental retardation, general hypotonicity, and a history of generalised oedema, cyanosis, heart murmur, and nystagmus in the first days of life was found to have both a translocation and a deletion. Her karyotype was 46,XX,del(21)t(18;21)(18p ter leads to 18q11::21q21 leads to 21qter;21pter leads to 21q11::18q11 leads to 18q ter). The karyotype of both parents was normal. The proposita is the result of a three break point exchange and is monosomic for part of the dark band q11 q21 of chromosome 21. It is suggested that in cases with mental retardation and apparent balanced de novo reciprocal translocation a small undetected deletion in one of the chromosomes involved in the translocation could explain the mental retardation.