Cytogenetic analysis of a one-month-old Japanese boy with cretinism-like features was carried out. His chromosome constitution was determined as 46, XY, -18, +der (18), t(3;18) (p24; q22) mat. A family study revealed that balanced translocation carriers were his mother and maternal grandmother. The propositus had characteristic features of 3p trisomy such as square facies, temporal indentation, strabimus, depressed nasal bridge, prominent middle upper lip, carp mouth, micro- and retrognathia, short neck and hypoplastic penis.
With the fin-culture technique, detailed karyotype studies were undertaken in Oryzias celebensis, particularly following C-banding and silver staining procedures. The chromosome number was 36 in diploid consisting of 4 pairs of meta-, 2 pairs of submeta-, and 12 pairs of acrocentrics (NF=48). The “large” biarmed chromosomes seemed to be produced by the mechanism of Robertsonian fusion. The smaller submetacentric pair consisted of satellited chromosomes with NORs on their satellited regions. Four meta- and submetacentric pairs showed characteristic C-bands on their short arms.