The aim of this study was to search for clinical and laboratorial data in 46,XY patients with ambiguous genitalia (AG) and normal testosterone (T) synthesis that could help to distinguish partial androgen insensitivity syndrome (PAIS) from 5-reductase type 2 deficiency (5-RD2) and from cases without molecular defects in the AR and SRD5A2 genes. Fifty-eight patients (51 families) were included. Age at first evaluation, weight and height at birth, consanguinity, familial recurrence, severity of AG, penile length, LH, FSH, T, dihydrotestosterone (DHT), 4-androstenedione (Δ4), and T/DHT and T/Δ4 ratios were evaluated. The AR and SRD5A2 genes were sequenced in all cases. There were 9 cases (7 families) of 5α-RD2, 10 cases (5 families) of PAIS, and 39 patients had normal molecular analysis of SRD5A2 and AR genes. Age at first evaluation, birth weight and height, and T/DHT ratio were lower in the undetermined group, while penile length was higher in this group. Consanguinity was more frequent and severity of AG was higher in 5α-RD2 patients. Familial recurrence was more frequent in PAIS patients. Birth weight and height, consanguinity, familial recurrence, severity of AG, penile length, and T/DHT ratio may help the investigation of 46,XY patients with AG and normal T synthesis. © 2012 Nélio Neves Veiga-Junior et al.2012 Lee, P.A., Houk, C.P., Ahmed, S.F., Hughes, I.A., Achermann, J., Ahmed, F., Baskin, L., Zucker, K., Consensus statement on management of intersex disorders (2006) Pediatrics, 118 (2), pp. 488-e500Imperato-Mcginley, J., Zhu, Y.S., Androgens and male physiology the syndrome of 5 -reductase-2 deficiency (2002) Molecular and Cellular Endocrinology, 198 (12), pp. 51-59Hughes, I.A., Deeb, A., Androgen resistance (2006) Best Practice and Research: Clinical Endocrinology and Metabolism, 20 (4), pp. 577-598. , DOI 10.1016/j.beem.2006.11.003, PII S1521690X0600087X, Hormone Resistance SyndromesCheon, C.K., Practical approach to steroid 5alpha-reductase type 2 deficiency (2010) European Journal of Pediatrics, 170 (1), pp. 1-8Galani, A., Kitsiou-Tzeli, S., Sofokleous, C., Kanavakis, E., Kalpini-Mavrou, A., Androgen insensitivity syndrome: Clinical features and molecular defects (2008) Hormones, 7 (3), pp. 217-229Mendona, B.B., Domenice, S., Arnhold, I.J.P., Costa, E.M.F., 46,XY disorders of sex development (DSD) (2009) Clinical Endocrinology, 70 (2), pp. 173-187Hussain, N., Chaghtai, A., Anthony Herndon, C.D., Herson, V.C., Rosenkrantz, T.S., McKenna, P.H., Hypospadias and early gestation growth restriction in infants (2002) Pediatrics, 109 (3), pp. 473-478. , DOI 10.1542/peds.109.3.473Morel, Y., Rey, R., Teinturier, C., Nicolino, M., Michel-Calemard, L., Mowszowicz, I., Jaubert, F., Josso, N., Aetiological diagnosis of male sex ambiguity: A collaborative study (2002) European Journal of Pediatrics, 161 (1), pp. 49-59Sinnecker, G.H.G., Hiort, O., Dibbelt, L., Albers, N., Drr, H.G., Hau, H., Heinrich, U., Kruse, K., Phenotypic classification of male pseudohermaphroditism due to steroid 5 -reductase 2 deficiency (1996) American Journal of Medical Genetics, 63 (1), pp. 223-230Ahmed, S.F., Khwaja, O., Hughes, I.A., The role of a clinical score in the assessment of ambiguous genitalia (2000) BJU International, 85 (1), pp. 120-124. , DOI 10.1046/j.1464-410X.2000.00354.xGabrich, P.N., Vasconcelos, J.S.P., Damiao, R., Da Silva, E.A., Penile anthropometry in Brazilian children and adolescents (2007) Jornal de Pediatria, 83 (5), pp. 441-446. , http://www.jped.com.br/conteudo/07-83-05-441/ing.pdf, DOI 10.2223/JPED.1671Tomasi, P.A., Sex determination, differentiation, and identity (2004) The New England Journal of Medicine, 350 (21), pp. 2204-2204Choi, J.H., Kim, G.H., Seo, E.J., Kim, K.S., Kim, S.H., Yoo, H.W., Molecular analysis of the AR and SRD5A2 genes in patients with 46,XY disorders of sex development (2008) Journal of Pediatric Endocrinology and Metabolism, 21 (6), pp. 545-553Wisniewski, A.B., Mazur, T., 46,XY DSD with female or ambiguous external genitalia at birth due to androgen insensitivity syndrome, 5alpha-reductase-2 deficiency, or 17beta-hydroxysteroid dehydrogenase deficiency: A review of quality of life outcomes (2009) International Journal of Pediatric Endocrinology, 2009, p. 7Praveen, E.P., Desai, A.K., Khurana, M.L., Philip, J., Eunice, M., Khadgawat, R., Kulshreshtha, B., Ammini, A.C., Gender identity of children and young adults with 5α-reductase deficiency (2008) Journal of Pediatric Endocrinology and Metabolism, 21 (2), pp. 173-179Maimoun, L., Philibert, P., Cammas, B., Audran, F., Bouchard, P., Fenichel, P., Cartigny, M., Sultan, C., Phenotypical, biological, and molecular heterogeneity of 5 -reductase deficiency: An extensive international experience of 55 patients (2011) The Journal of Clinical Endocrinology Metabolism, 96 (2), pp. 296-307Cohen-Kettenis, P.T., Gender change in 46,XY persons with 5α-reductase-2 deficiency and 17β-hydroxysteroid dehydrogenase-3 deficiency (2005) Archives of Sexual Behavior, 34 (4), pp. 399-410. , DOI 10.1007/s10508-005-4339-4Imperato-McGinley, J., Peterson, R.E., Gautier, T., Sturla, E., Androgens and the evolution of male-gender identity among male pseudohermaphrodites with 5α-reductase deficiency (1979) New England Journal of Medicine, 300 (22), pp. 1233-1237Nakamoto, J., Fuqua, J.S., Laboratory assays in pediatric endocrinology: Common aspects (2007) Pediatric Endocrinology Reviews, 5 (SUPPL. 1), pp. 539-554George, M.M., New, M.I., Ten, S., Sultan, C., Bhangoo, A., The clinical and molecular heterogeneity of 17 HSD-3 enzyme deficiency (2010) Hormone Research in Paediatrics, 74 (4), pp. 229-240Ahmed, S.F., Cheng, A., Dovey, L., Hawkins, J.R., Martin, H., Rowland, J., Shimura, N., Hughes, I.A., Phenotypic features, androgen receptor binding, and mutational analysis in 278 clinical cases reported as androgen insensitivity syndrome (2000) Journal of Clinical Endocrinology and Metabolism, 85 (2), pp. 658-665. , DOI 10.1210/jc.85.2.658Boehmer, A.L.M., Bruggenwirth, H., Van Assendelft, C., Otten, B.J., Verleun-Mooijman, M.C.T., Niermeijer, M.F., Brunner, H.G., Drop, S.L.S., Genotype Versus phenotype in families with androgen insensitivity syndrome (2001) Journal of Clinical Endocrinology and Metabolism, 86 (9), pp. 4151-4160. , DOI 10.1210/jc.86.9.4151Vottero, A., Minari, R., Viani, I., Evidence for epigenetic abnormalities of the androgen receptor gene in foreskin from children with hypospadias (2011) The Journal of Clinical Endocrinology Metabolism, 96 (12), pp. 1953-E1962De Andrade MacHado Neto, F., Moreno Morcillo, A., Trevas Maciel-Guerra, A., Guerra-Junior, G., Idiopathic male pseudohermaphroditism is associated with prenatal growth retardation (2005) European Journal of Pediatrics, 164 (5), pp. 287-291. , DOI 10.1007/s00431-005-1626-yScaramuzzo, R.T., Boldrini, A., Bertelloni, S., Parrini, D., Serino, L., Ghirri, P., Low testosterone levels in pre-term newborns born small for gestational age (2010) Journal of Endocrinological Investigation, 33 (4), pp. 215-217Rhind, S.M., Rae, M.T., Nigel Brooks, A., Effects of nutrition and environmental factors on the fetal programming of the reproductive axis (2001) Reproduction, 122 (2), pp. 205-214Wu, G., Bazer, F.W., Cudd, T.A., Meininger, C.J., Spencer, T.E., Maternal nutrition and fetal development (2004) Journal of Nutrition, 134 (9), pp. 2169-2172Schoeters, G., Den Hond, E., Dhooge, W., Van Larebeke, N., Leijs, M., Endocrine disruptors and abnormalities of pubertal development (2008) Basic and Clinical Pharmacology and Toxicology, 102 (2), pp. 168-175. , DOI 10.1111/j.1742-7843.2007.00180.xZen, S., Darcan, S., Effects of environmental endocrine disruptors on pubertal development (2011) JCRPE, 3 (1), pp. 1-6Edwards, T.M., Moore, B.C., Guillette, Jr.L.J., Olea, N., McLachlan, J., Page, D., Reproductive dysgenesis in wildlife: A comparative view (2006) International Journal of Andrology, 29 (1), pp. 109-121Paris, F., Jeandel, C., Servant, N., Sultan, C., Increased serum estrogenic bioactivity in three male newborns with ambiguous genitalia: A potential consequence of prenatal exposure to environmental endocrine disruptors (2006) Environmental Research, 100 (1), pp. 39-43. , DOI 10.1016/j.envres.2005.06.001, PII S0013935105000861Nicoletti, A., Baldazzi, L., Balsamo, A., Barp, L., Pirazzoli, P., Gennari, M., Radetti, G., Cicognani, A., SRD5A2 gene analysis in an Italian population of under-masculinized 46,XY subjects (2005) Clinical Endocrinology, 63 (4), pp. 375-380. , DOI 10.1111/j.1365-2265.2005.02348.x