A NEW OBSERVATION OF 13q DELETION SYNDROME: SEVERE UNDESCRIBED FEATURES.

Summary: A new observation of I3q deletion syndrome: severe undescribed features: 13q deletion syndrome is characterized by a wide phenotypic spectrum resulting from a partial deletion of the long arm of chromosome 13. It consists predominantly of mental and motor retardation, craniofacial dysmorphia, growth retardation, and several congenital malformations. We present a new case with 13q deletion syndrome phenotypically characterized by severe major malformations, some of them still undescribed, consisting of left diaphragmatic hernia, right pulmonary sequestration, hypoplastic left heart syndrome, pancreatic agenesis, polysplenia, and catastrophic central nervous system malformations: semilobar holoprosencephaly, occipital myelomeningocele, partial agenesis of the corpus callosum and agenesis of olfactory bulbs. Fluorescence in situ hybridization technique using the probe LSI DI3S3I9 ( 13q 14) SO/ LSI 13q34 SG determined partial monosomy of chromosome 13 in 39/100 cells (mosaicism).Key-words: 13q deletion - Proboscis - Floloprosencephaly - Diaphragmatic hernia.INTRODUCTION13q deletion syndrome is characterized by a wide phenotypic spectrum resulting from a partial deletion of the long arm of chromosome 13. It consists predominantly of mental and motor retardation, craniofacial dysmorphia, growth retardation, and several congenital malformations (microcephaly, trigonocephaly, broad prominent nasal bridge, hypertelorism, microphthalmus, epicanthus, ptosis, coloboma of the iris, protunding upper incisors, micrognathia, short neck with lateral neck folds, low set malformed ears, large malroted ears, facial asymmetry...), growth retardation, and various congenital malformations (retinoblastoma, congenital heart disease, imperforate anus, perineal fistula, hypo/epispadias, undescended testes with bifid scrotum, pelvic girdle anomalies, foot and toe anomalies, thumb absent or hypoplastic, fourth finger short) (1,6,8).The first attempts to describe this syndrome were carried out by Allderdice et al. in 1969, collecting cases from approximately 1963 (1). Large numbers of patients with interstitial deletions of the long arm of chromosome 13 have been described over the past 30 years.The phenotypes of such patients have varied widely. In 1977, Niebuhr defined four categories of patients on the basis of physical and cytogenetic findings (9). He observed that those patients with distal deletions were the most severely affected and that those with more proximal deletions tended to have fewer major anomalies, except for retinoblastoma.CLINICAL REPORTA woman 25 years old, in her first gestation (not controlled), was admitted to hospital with signs of labor. Her partner, 30 years old, was healthy and there was no consanguinity between them. An ultrasound found a 31 weeks female with a severe polymalformative syndrome and polyhydramnios. Eutocic delivery, Apgar 4-4-5. Anencephaly was observed, so the physician team decided not to resuscitate. Exitus occurred 50 minutes later. Phenotypical examination showed lack of skull, semilobar holoprosencephaly, occipital encephalocele, microcephaly, microophtalmia, hypotelorism, proboscis, long low-set ears, long philtrum, small mouth, two natal teeth, microretrognathism and short webbed neck (Figs 1-2). She weighed 990 grams and measured 33 centimeters, both appropriate for gestational age.Necropsy showed wide left diaphragmatic hernia, right pulmonary sequestration, hypoplastic left heart syndrome with interventricular communication, pancreatic agenesis, polysplenia, and the aforementioned catastrophic central nervous system malformations: occipital encephalocele, semilobar holoprosencephaly with hypoplasia and fusion of frontal lobes, periventricular calcifications, partial agenesis of corpus callosum, agenesis of olfactory bulbs and completely unstructured brainstem.Fluorescence in situ hybridization technique using the probe LSI D13S319 (13ql4) SO/ LSI 13q34 SG determined partial monosomy of chromosome 13 (widely deleted long arm of chromosome 13) in 39/100 cells (mosaicism). …