An 18p21q Translocation in a Patient With Presumptive "Monosomy G"

Abstract

Fig 1.-Patient phenotype.A 3\m=1/2\-year-old retarded girl had multiple congenital anomalies. Cytogenetic analysis revealed a karyotype with a modal number of 2N = 45 and one member of the G (21-22) group consistently absent in lymphocytes and skin fibroblasts. The original diagnosis was "monosomy G" but reanalysis following fluorescence and Giemsa banding techniques demonstrated a translocation involving chromosomes 18 and 21 (45,XX, t[18p21q]). The patient therefore possesses the 18p-syndrome and her phenotypic findings are compatible.Compl ete autosomal monosomy in man is commonly considered to represent a lethal condition. Nonethe¬ less, published reports have described three presumptively viable monosomic patients with complete loss (nonmosaic) of a G (21-22) group chromo¬ some.13 A mentally retarded girl had multiple congenital abnormalities and had received a diagnosis of "monosomy G"; but after a reexam¬ inaron that utilized the recently de¬ veloped staining techniques allowing positive homologue identification she was found to possess a clearly distin¬ guishable translocation between chro¬ mosomes 21 and 18 (45,XX, t[18p21q]). Report of a CaseThe patient, a 3%-year-oId girl, was the 1,450 gm (3% lb) product of a 33-week ges¬ tation to a 23-year-old gravida III, para I, abortion I white mother. Bleeding during the first trimester and again txk weeks prior to delivery was the only complication of pregnancy. The baby did poorly in the premature nursery, with slow weight gain and apneic spells. On the fifth day of life a grade /VI systolic ejection murmur was heard over the precordium. The baby sub¬ sequently developed cardiac failure and catheterization revealed a patent ductus arteriosus, which was ligated at 3 months of age. Since that time she has failed to thrive despite a 150 calorie/kg/day intake.The child manifests the following char¬ acteristics (Fig 1): height and weight be¬ low the third percentile; head size con¬ comitant with height and weight, but also well below the third percentile; hypertelorism; marked ptosis; low-set, lop ears; carp mouth; and patent ductus arteriosus.She attained a developmental level of 29 months at 42 months of age (develop¬ mental quotient of 65) and is therefore considered moderately retarded.Normal values for the following labora¬ tory tests were noted: complete blood cell count, urinalysis, serum electrolytes, alka¬ line phosphatase, blood urea nitrogen,

Double deletion of a chromosome 21 inserted in a chromosome 22 in an azoospermic patient

“…A few years ago, monosomy 21 was thought to be the only viable autosomic monosomy. However, most of the reported cases turned out to be partial monosomies resulting from cryptic translocations or mosaics [4,8,10,12,15,20,22].…”

Heterotaxy with left atrial isomerism in a patient with deletion 18p

“…Specific anatomic types are shown in Table II. A variety of CHDs is noticeable [Coetsier and Orye, 1967; Vaillaud et al, 1970; Giraud et al, 1971; Cohen and Putnam, 1972; Faust et al, 1976; Nakano et al, 1977; Pearl, 1989; Movahhedian et al, 1991; Kane et al 1991; El Kalla et al, 1992; Telvi et al, 1995; Nazarenko et al, 1999]. Interestingly, situs abnormalities were diagnosed in three patients.…”

An 18p- syndrome due to 15/18 translocation with facial palsy and deafness.

“…As to 18p-due to a centric fusion translocation, 13 cases (Pfeiffer 1969;Miller et al 1970;Malpuech et al 1971;Subrt et al 1971;Cohen and Patnam 1972;Fraccaro et al 1972 ;Gilgenkrantz et al 1972;Leisti et al 1973;Kistenmacher et al 1974;Schinzel et al 1974;Funderburk et al 1977;Serille et al 1977) have been reported. Six of the 13 cases were fusions with Gq and the other seven were with Dq.…”